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Biology subjects

Chen, G.

Publications and source records attributed to Chen, G..

At least 199 records · Page 11Linked to original sources

EquiScore: A generic protein-ligand interaction scoring method integrating physical prior knowledge with data augmentation modeling

Developing robust methods for evaluating protein-ligand interactions has been a long-standing problem. Here, we propose a novel approach called EquiScore, which utilizes an equivariant heterogeneous graph neural network to integrate physical prior knowledge and characterize protein-ligand interactions in equivariant geometric space. To improve generalization performance, we constructed a dataset called PDBscreen and designed multiple data augmentation strategies suitable for training scoring methods. We also analyzed potential risks of data leakage in commonly used data-driven modeling processes and proposed a more stringent redundancy removal scheme to alleviate this problem. On two large external test sets, EquiScore outperformed 21 methods across a range of screening performance metrics, and this performance was insensitive to binding pose generation methods. EquiScore also showed good performance on the activity ranking task of a series of structural analogs, indicating its potential to guide lead compound optimization. Finally, we investigated different levels of interpretability of EquiScore, which may provide more insights into structure-based drug design.

bioinformatics↗

Evolution of Shewanella oneidensis MR-1 in competition with Citrobacter freundii

Interspecific competition is one of the most important metabolic interactions within microbial communities, and exoelectrogenic bacteria that can conduct extracellular electron transfer act essential roles in nature and engineering systems for pollutants removal. In the present study we investigated the long-term impact of substrate competition from non-exoelectrogenic Citrobacter freundii An1 on exoelectrogenic Shewanella oneidensis MR-1. Without additional electron acceptor or with electron acceptor of oxygen, C. freundii An1 typically suppressed the growth of S. oneidensis MR-1. In contrast, S. oneidensis MR-1 grown better with electron acceptor of ferrihydrite by taking advantage of extracellular electron transfer. However, the presence of ferrihydrite did not enhance the ferrihydrite reduction of S. oneidensis MR-1 after the 160 d-acclimation. The whole genome resequencing showed a complex evolution of S. oneidensis MR-1 when the strain faced the competition from C. freundii An1 for substrate.

microbiology↗

Cryo-EM structure of the human G-protein coupled receptor 1 (GPR1) - Gi protein complex bound to the chemerin C-terminal nonapeptide

Chemerin is an adipokine with chemotactic activity to a subset of leukocytes. Chemerin mainly acts through its C-terminal nonapeptide (YFPGQFAFS, C9) that bind to three G protein-coupled receptors including chemokine-like receptor 1 (CMKLR1), G-protein coupled receptor 1 (GPR1) and C-C chemokine receptor-like 2 (CCRL2). We examined C9 signaling through GPR1 and found this receptor capable of Gi signaling but very weak {beta}-arrestin signaling. Here we report high-resolution cryo-EM structures of GPR1-Gi complexes bound to full-length chemerin and to C9, respectively. Unlike C9 that inserts directly into a transmembrane binding pocket, full-length chemerin uses its N-terminal globular core for extensive interaction with the N terminus of GPR1. Within the binding pocket, the C terminal loop containing the nonapeptide takes the same "S-shape" pose as synthetic C9 nonapeptide. These findings explain why the nonapeptide is a full agonist of GPR1, and demonstrate that chemerin uses a "two-site" model for interaction with GPR1. An analysis of the GPR1-Gi protein interface found high similarities to the CMKLR1-Gi complex, as confirmed by site-directed mutagenesis with functional verifications. Our structural analysis demonstrates shared features with chemokines in that chemerin acts as a "reverse chemokine" with switched functions of its N and C termini in the interaction with GPR1.

pharmacology and toxicology↗

Molecular Evolution and Interaction of 14-3-3 Proteins with H+-ATPases in Plant Abiotic Stresses

Environmental stresses severely affect plant growth and crop productivity. Regulated by 14-3-3 proteins (14-3-3s), H+-ATPases (AHA) are important proton pumps that can induce diverse secondary transport via channels and co-transporters for the abiotic stress response of plants. Many studies demonstrated the roles of 14-3-3s and AHAs in coordinating the processes of plant growth, phytohormone signaling, and stress responses. However, the molecular evolution of 14-3-3s and AHAs has not been summarized in parallel with insights across multiple plant species. Here, we review the roles of 14-3-3s and AHAs in cell signaling to enhance plant responses to diverse environmental stresses. We analyzed the molecular evolution of key proteins that are associated with 14-3-3s and AHAs in plant growth and hormone signaling. The results revealed evolution, duplication, contraction, and expansion of 14-3-3s and AHAs in green plants. We also discussed the stress-specific expression of those 14-3-3s and AHAs in a eudicot (Arabidopsis thaliana), a monocot (Hordeum vulgare) and a moss (Physcomitrium patens) under abiotic stresses. We propose that 14-3-3s and H+-ATPases respond to abiotic stresses through many important targets and signaling components of phytohormones, which could be promising to improve plant tolerance to single or multiple environmental stresses. HighlightWe review the response and adaptation of 14-3-3s and AHAs to diverse environmental stimuli and we analyze the evolutionary features and molecular functions of 14-3-3s and AHAs.

plant biology↗

Neural response properties predict perceived contents and locations elicited by intracranial electrical stimulation of human auditory cortex

Intracranial electrical stimulation (iES) of auditory cortex can elicit sound experiences with a variety of perceived contents (hallucination or illusion) and locations (contralateral or bilateral side), independent of actual acoustic inputs. However, the neural mechanisms underlying this elicitation heterogeneity remain undiscovered. Here, we collected subjective reports following iES at 3062 intracranial sites in 28 patients and identified 113 auditory cortical sites with iES-elicited sound experiences. We then decomposed the sound-induced intracranial electroencephalogram (iEEG) signals recorded from all 113 sites into time-frequency features. We found that the iES-elicited perceived contents can be predicted by the early high-{gamma} features extract from sound-induced iEEG. In contrast, the perceived locations elicited by stimulating hallucination sites and illusion sites are determined by the late high-{gamma} and long-lasting features, respectively. Our study unveils the crucial neural signatures of iES-elicited sound experiences in human and presents a new strategy to hearing restoration for individuals suffering from deafness.

neuroscience↗

Data-based large-scale models provide a window into the organization of cortical computations

The neocortex of the brain is one of the most powerful computing devices that exists, but it remains largely open how its computations are organized. Since the neocortex is a 2D tapestry consisting of repeating stereotypical local cortical microcircuits, a key step for solving this problem is to understand how cortical microcircuits compute. We know by now a lot about their connectivity structure and their neuron types, but we are lacking tools for elucidating causal relations between this structure and their computational function. We present a new tool for elucidating this relation: We train large-scale models of cortical microcircuits, which integrate most current knowledge about their structure, for carrying out similar computational tasks as in the brain. We show that the trained model achieves a similar computational performance as the brain, and that it reproduces experimentally found traits of cortical computation and coding that do not appear in neural network models from AI. Furthermore, we reverse-engineer how computations are organized in the model, thereby producing specific hypotheses that can be tested in experimental neuroscience. Altogether we show that cortical microcircuits provide a distinct new neural network paradigm that is of particular interest for neuromorphic engineering because it computes with highly energy-efficient sparse activity. TeaserReverse engineering of cortical computations

neuroscience↗

Superior colliculus cell types bidirectionally modulate choice activity in frontal cortex

Action selection occurs through competition between potential choice options. Neural correlates of choice competition are observed across frontal cortex and downstream superior colliculus (SC) during decision-making, yet how these regions interact to mediate choice competition remains unresolved. Here we report that cell types within SC can bidirectionally modulate choice competition and drive choice activity in frontal cortex. In the mouse, topographically matched regions of frontal cortex and SC formed a descending motor pathway for directional licking and a re-entrant loop via the thalamus. During decision-making, distinct neuronal populations in both frontal cortex and SC encoded opposing lick directions and exhibited push-pull dynamics. SC GABAergic neurons encoded ipsilateral choice and glutamatergic neurons encoded contralateral choice, and activating or suppressing these cell types could bidirectionally drive push-pull choice activity in frontal cortex. These results thus identify SC as a major locus to modulate choice competition within the broader action selection network.

neuroscience↗

Unbiased discovery of natural sequence variants that influence fungal virulence

Isolates of Cryptococcus neoformans, a fungal pathogen that kills over 120,000 people each year, differ from a 19-megabase reference genome at a few thousand up to almost a million DNA sequence positions. We used bulked segregant analysis and association analysis, genetic methods that require no prior knowledge of sequence function, to address the key question of which naturally occurring sequence variants influence fungal virulence. We identified a region containing such variants, prioritized them, and engineered strains to test our findings in a mouse model of infection. At one locus we identified a 4-nt variant in the PDE2 gene, which severely truncates its phosphodiesterase product and significantly alters virulence. Our studies demonstrate a powerful and unbiased strategy for identifying key genomic regions in the absence of prior information, suggest revisions to current assumptions about cAMP levels and about common laboratory strains, and provide significant sequence and strain resources to the community.

microbiology↗

Doxorubicin inhibits phosphatidylserine decarboxylase and confers broad-spectrum antifungal activity

O_LIAs phospholipids of cell membranes, phosphatidylethanolamine (PE) and phosphatidylserine (PS) play crucial roles in glycerophospholipid metabolism. Broadly, some phospholipid biosynthesis enzymes serve as potential fungicide targets. Therefore, revealing the functions and mechanism of PE biosynthesis in plant pathogens would provide potential targets for crop disease control. C_LIO_LIWe performed analyses including phenotypic characterizations, lipidomics, enzyme activity, site-directed mutagenesis, and chemical inhibition assays to study the function of PS decarboxylase-encoding gene MoPSD2 in rice blast fungus Magnaporthe oryzae. C_LIO_LIThe Mopsd2 mutant was defective in development, lipid metabolism and plant infection. The PS level increased while PE decreased in Mopsd2, consistent with the enzyme activity. Furthermore, chemical doxorubicin inhibited the enzyme activity of MoPsd2 and showed antifungal activity against ten phytopathogenic fungi including M. oryzae and reduced disease severity of two crop diseases in the field. Three predicted doxorubicin-interacting residues are important for MoPsd2 functions. C_LIO_LIOur study demonstrates that MoPsd2 is involved in de novo PE biosynthesis and contributes to the development and plant infection of M. oryzae and that doxorubicin shows broad-spectrum antifungal activity as a fungicide candidate. The study also implicates that bacterium Streptomyces peucetius, which biosynthesizes doxorubicin, could be potentially used as an eco-friendly biocontrol agent. C_LI

pathology↗

XMAP: Cross-population fine-mapping by leveraging genetic diversity and accounting for confounding bias

Fine-mapping prioritizes risk variants identified by genome-wide association studies (GWASs), serving as a critical step to uncover biological mechanisms underlying complex traits. However, several major challenges still remain for existing fine-mapping methods. First, the strong linkage disequilibrium among variants can limit the statistical power and resolution of fine-mapping. Second, it is computationally expensive to simultaneously search for multiple causal variants. Third, the confounding bias hidden in GWAS summary statistics can produce spurious signals. To address these challenges, we develop a statistical method for cross-population fine-mapping (XMAP) by leveraging genetic diversity and accounting for confounding bias. By using cross-population GWAS summary statistics from global biobanks and genomic consortia, we show that XMAP can achieve greater statistical power, better control of false positive rate, and substantially higher computational efficiency for identifying multiple causal signals, compared to existing methods. Importantly, we show that the output of XMAP can be integrated with single-cell datasets, which greatly improves the interpretation of putative causal variants in their cellular context at single-cell resolution.

genetics↗

Structural insights into ligand recognition and selectivity of the human hydroxycarboxylic acid receptor HCAR2

Hydroxycarboxylic acid receptor 2 (HCAR2) belongs to the family of class A G-protein-coupled receptors with key roles in regulating lipolysis and free fatty acid formation in humans. It is deeply involved in many pathophysiological processes and serves as an attractive target for the treatment of neoplastic, autoimmune, neurodegenerative, inflammatory, and metabolic diseases. Here, we report four cryo-EM structures of human HCAR2-Gi1 complexes with or without agonists, including the drugs niacin and acipimox, and the highly subtype-specific agonist MK-6892. Combined with molecular docking and functional analysis, we have revealed the recognition mechanism of HCAR2 for different agonists and summarized the general pharmacophore features of HCAR2 agonists, which are based on three key residues R1113.36, S17945.52, and Y2847.43. Notably, the MK-6892-HCAR2 structure shows an extended binding pocket relative to other agonist-bound HCAR2 complexes. In addition, the key residues that determine the ligand selectivity between the HCAR2 and HCAR3 are also illuminated. Our findings provide structural insights into the ligand recognition, selectivity, activation, and G protein coupling mechanism of HCAR2, which sheds light on the design of new HCAR2-targeting drugs for greater efficacy, higher selectivity, and fewer or no side effects.

cell biology↗

Accurate prediction of transcriptional activity of single missense variants in HIV Tat with deep learning

Tat is an essential gene for increasing the transcription of all HIV genes, and it affects HIV replication, HIV exit from latency, and AIDS progression. The Tat gene frequently mutates in vivo producing variants with diverse activities, contributing to HIV viral heterogeneity, as well as drug-resistant clones. Thus, identifying the transcriptional activities of Tat variants will help to better understand AIDS pathology and treatment. We recently reported the missense mutation landscape of all single amino acid Tat variants. In these experiments, a fraction of double missense alleles exhibited intragenic epistasis. It is too time-consuming and costly to determine a variants effect for all double mutant alleles with experiments. Therefore, we propose a combined GigaAssay/Deep learning approach. As a first step for determining activity landscapes for complex variants, we evaluated a deep learning framework using previously reported GigaAssay experiments to predict how transcription activity is affected by Tat variants with single missense substitutions. Our approach achieves a 0.94 Pearson correlation coefficient when comparing experimental to predicted activities. This hybrid approach should be extensible to more complex Tat alleles for better understanding the genetic control of HIV genome transcription.

bioinformatics↗

Potentiation of host defense through sRNA packaged in OMVs of Xanthomonas oryzae pv. oryzicola

Bacterial outer membrane vesicles (OMVs)-packaged delivery of noncoding small RNAs (sRNAs) can function as novel mediators of interspecies communication. However, the role of which in the interaction between phytopathogenic bacteria and their host plants is unclear. In this study, we characterized differentially packaged sRNAs in Xanthomonas oryzae pv. oryzicola (Xoc) BLS256 OMVs using RNA-Seq, and we selected the most abundant sRNA Xosr001 for further study based on its essential role in the induction of stomatal immunity in rice. Xoc loads Xosr001 into OMVs, which are transferred specifically into the mechanical tissues of rice leaves. We uncovered that OMVs-mediated Xosr001 inhibitors attenuated OsJMT1 transcripts in vivo and reduced the endogenous MeJA contents in rice leaves. Stomatal conductance was measured to show that {Delta}Xosr001 mutant weakened the ability of stomatal re-opening on rice leaves after spray inoculation. Most notably, the transgenic rice lines OsJMT1-HA-OE exhibited attenuated stomatal immunity and disease susceptibility after {Delta}Xosr001 infection compared with Xoc infection. These results define that Xosr001 packaged in Xoc OMVs highlights a smart molecular mechanism to activate stomatal immunity in rice.

plant biology↗

A regulatory circuit involving the NADH dehydrogenase-like complex balances C4 photosynthetic carbon flow and cellular redox in maize

O_LIC4 plants typically operate a CO2 concentration mechanism from mesophyll (M) cells into bundle sheath (BS) cells. NADH dehydrogenase-like (NDH) complex is enriched in the BS cells of many NADP-ME type C4 plants, and is more abundant in C4 than in C3 plants, but to what extent it is involved in the CO2 concentration mechanism remains to be experimentally investigated. C_LIO_LIWe created maize and rice mutants deficient in NDH function, and used a combination of transcriptomic, proteomic, and metabolomic approaches for comparative analysis. C_LIO_LIConsiderable decrease in growth, photosynthetic activities, and levels of key photosynthetic proteins were observed in maize but not rice mutants. However, gene expression for many cyclic electron transport and Calvin-Benson cycle components plus BS specific C4 enzymes, was up-regulated in maize mutants. Metabolite analysis of the maize ndh mutants revealed increased NADPH/NADP ratio, as well as malate, RuBP, FBP, and photorespiration components. C_LIO_LIWe suggest that by optimizing NADPH and malate levels, adjusting NADP-ME activity, NDH functions to balance metabolic and redox states in the BS cells of maize, coordinating photosynthetic gene expression and protein content, thus directly regulating the carbon flow in the two-celled C4 system of maize. C_LI

plant biology↗

A promising QTL QSns.sau-MC-3D.1 likely superior to WAPO1 for wheat spikelet number per spike shows no adverse effects on yield-related traits

Spikelet number per spike (SNS) is one of the crucial factors determining wheat yield. Thus, improving our understanding of the genes that regulate SNS could help develop higher-yielding wheat varieties. A genetic linkage map constructed using the GenoBaits Wheat 16K Panel and the 660K SNP array contained 5991 polymorphic SNP markers spanning 2813.26 cM. A total of twelve QTL for SNS were detected in the recombinant inbred line (RIL) population msf x Chuannong 16 (MC), and two of them, i.e., QSns.sau-MC-3D.1 and QSns.sau-MC-7A, were stably expressed. QSns.sau-MC-3D.1 had high LOD values ranging from 4.99 to 11.06 and explained 9.71-16.75% of the phenotypic variation. Comparison of QSns.sau-MC-3D.1 with previously reported SNS QTL suggested that it is likely a novel one. A kompetitive allele-specific PCR (KASP) marker, KASP-10, tightly linked to QSns.sau-MC-3D.1 was developed to successfully validate its effect in three segregated populations and a natural population. Genetic analysis indicated that WHEAT ORTHOLOG OFAPO1 (WAPO1) was a candidate gene for QSns.sau-MC-7A. The combined additive effect of QSns.sau-MC-3D.1 and WAP01 had a great additive effect increasing SNS by 7.10%. In addition, our results suggested that SNS is not affected by 1BL/1RS translocations in the MC RIL population. Correlation analysis between two major QTL and other agronomic traits showed that QSns.sau-MC-3D.1 was likely independent of these agronomic traits. However, the H2 haplotype of WAPO1 may affect effective tiller number and plant height. This indicated that the breeding potential of QSns.sau-MC-3D.1 is better than that of WAPO1. The geographical distribution of QSns.nsau-MC-3D.1 showed that QSns.sau-MC-3D.1 positive allele frequency was dominant in most wheat-producing regions of China and it has been positively selected among modern cultivars released in China since the 1940s. Two genes, TraesCS3D03G0222600 and TraesCS3D03G0216800, associated with SNS development were predicted in the physical interval of QSns.sau-MC-3D.1. qRT-PCR results of the two genes showed that only the expression level of TraesCS3D03G0216800 was significantly different between msf and CN16. These results enrich our understanding of the genetic basis of wheat SNS and will be useful for fine mapping and cloning of genes underlying QSns.sau-MC-3D.1, and provide a basis for marker-assisted selection breeding. Author summaryIn this study, we identified two major QTL (QSns.sau-MC-3D.1 and QSns.sau-MC-7A) in a RIL population. WAPO1 was demonstrated to be the candidate gene for QSns.sau-MC-7A. QSns.sau-MC-3D.1 was a novel and stably expressed QTL, and further confirmed in different genetic backgrounds. Our results further demonstrate that QSns.sau-MC-3D.1 has better breeding potential because of its no adverse effect on other agronomic traits than WAPO1, and it has been positively selected during Chinese breeding programs since the 1940s. Taken together, the identification of QSns.sau-MC-3D.1 offers a promising resource to further increase wheat yields.

genetics↗

BOLD response is more than just magnitude: improving detection sensitivity through capturing hemodynamic profiles

Typical FMRI analyses assume a canonical hemodynamic response function (HRF) with a focus on the overshoot peak height, while other morphological aspects are largely ignored. Thus, in most reported analyses, the overall effect is reduced from a curve to a single scalar. Here, we adopt a data-driven approach to HRF estimation at the whole-brain voxel level, without assuming a response profile at the individual level. Then, we estimate the response in its entirety with a roughness penalty at the population level to improve predictive accuracy, inferential efficiency, and cross-study reproducibility. Using a fast event-related FMRI dataset, we demonstrate the extent of under-fitting and information loss that occurs when adopting the canonical approach. We also address the following questions: O_LIHow much does the HRF shape vary across regions, conditions, and groups? C_LIO_LIDoes an agnostic approach improve sensitivity to detect an effect compared to an assumed HRF? C_LIO_LICan examining HRF shape help validate the presence of an effect complementing statistical evidence? C_LIO_LICould the HRF shape provide evidence for whole-brain BOLD response during a simple task? C_LI

neuroscience↗

Effect of Total Sphingomyelin Synthase Activity on Low Density Lipoprotein Catabolism in Mice

BackgroundSphingomyelin (SM) and cholesterol are two key lipid partners on cell membranes and on lipoproteins. Many studies have indicated the influence of cholesterol on SM metabolism. This study examined the influence of SM biosynthesis on cholesterol metabolism. MethodsInducible global Sms1 KO/global Sms2 KO mice were prepared to evaluate the effect of whole-body SM biosynthesis deficiency on lipoprotein metabolism. Tissue cholesterol, SM, ceramide, and glucosylceramide levels were measured. TG production rate and LDL catabolism were measured. Lipid rafts were isolated and LDL receptor mass and function were evaluated. Also, the effects of exogenous sphingolipids on hepatocytes were investigated. ResultsWe found that total SMS depletion significantly reduced plasma SM levels. Also, the total deficiency significantly induced plasma cholesterol, apoB, and apoE levels. Importantly, total SMS deficiency, but not SMS2 deficiency, dramatically decreased LDL receptors in the liver and attenuated LDL uptake through the receptor. Further, we found that total SMS deficiency greatly reduced LDL receptors in the lipid rafts which contained significantly lower SM and significantly higher glucosylceramide as well as cholesterol. Furthermore, we treated primary hepatocytes and Huh7 cells (a human hepatoma cell line) with SM, ceramide, or glucosylceramide, and we found that only SM could up-regulate LDL receptor levels in a dose-dependent fashion. ConclusionsWhole-body SM biosynthesis plays an important role in LDL-cholesterol catabolism. The total SMS deficiency, but not SMS2 deficiency, reduces LDL uptake and causes LDL-cholesterol accumulation in the circulation. Given the fact that serum SM level is a risk factor for cardiovascular diseases, inhibiting SMS2 but not SMS1 should be the desirable approach. Graphic Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=175 SRC="FIGDIR/small/527088v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@50757eorg.highwire.dtl.DTLVardef@51ad9dorg.highwire.dtl.DTLVardef@5d362corg.highwire.dtl.DTLVardef@18fbe63_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

Protein Sequence Design by Entropy-based Iterative Refinement

Inverse Protein Folding (IPF) is an important task of protein design, which aims to design sequences compatible with a given backbone structure. Despite the prosperous development of algorithms for this task, existing methods tend to leverage limited and noisy residue environment when generating sequences. In this paper, we develop an iterative sequence refinement pipeline, which can refine the sequence generated by existing sequence design models. It selects and retains reliable predictions based on the models confidence in predicted distributions, and decodes the residue type based on a partially visible environment. The proposed scheme can consistently improve the performance of a number of IPF models on several sequence design benchmarks, and increase sequence recovery of the SOTA model by up to 10%. We finally show that the proposed model can be applied to redesign Transposon-associated transposase B. 8 variants exhibit improved gene editing activity among the 20 variants we proposed. Our code and a demo of the refinement pipeline are provided in the online colab.

bioinformatics↗