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Biology subjects

Yan, Y.

Publications and source records attributed to Yan, Y..

At least 271 records · Page 15Linked to original sources

Chemically Induced Chromosomal Interaction (CICI): A New Tool to Study Chromosome Dynamics and Its Biological Roles

Numerous intra- and inter-chromosomal contacts have been mapped in eukaryotic genomes, but it remains challenging to link these 3D structures to their regulatory functions. To establish the causal relationships between chromosome conformation and genome functions, we need a method that allows us to selectively perturb the conformation at targeted loci. Here, we developed a method in budding yeast, Chemically Induced Chromosomal Interaction (CICI), to engineer long-distance chromosomal interactions selectively and dynamically. We implemented CICI at multiple intra- and inter-chromosomal loci pairs and showed that CICI can form in >50% of cells, even between loci with very low Hi-C contact frequencies. CICI formation is slower at these low Hi-C sites, revealing the dynamic nature of the Hi-C signals. As a functional test, we forced the interaction between mating-type locus (MAT) and HMR and observed significant change in donor preference during mating-type switching, showing that chromosome conformation plays an important role in homology-directed DNA repair. Overall, these results demonstrate that CICI is a powerful tool to study chromosome dynamics and the 3D genome function.

synthetic biology↗

CDE-1 suppresses the production of risiRNA by coupling polyuridylation and degradation of 26S rRNA

Antisense ribosomal siRNAs (risiRNAs) downregulate pre-rRNAs through the nuclear RNAi pathway in Caenorhabditis elegans. However, the biogenesis and regulation of risiRNAs remain obscure. Previously, we showed that 26S rRNAs are uridylated at the 3-ends by an unknown terminal polyuridylation polymerase before the rRNAs are degraded by a 3 to 5 exoribonuclease SUSI-1(ceDIS3L2). There are three polyuridylation polymerases, CDE-1, PUP-2, and PUP-3, in C. elegans. Here, we found that CDE-1 is specifically involved in suppressing risiRNA production. CDE-1 localizes to perinuclear granules in the germline and uridylates both Argonaute-associated 22G-RNAs and 26S rRNAs at the 3-ends. Immunoprecipitation followed by mass spectrometry (IP-MS) revealed that CDE-1 interacts with SUSI-1(ceDIS3L2). Consistent with those results, both CDE-1 and SUSI-1(ceDIS3L2) are required for the inheritance of RNAi. Therefore, this work identified a rRNA surveillance machinery of rRNAs that couples terminal polyuridylation and degradation.

molecular biology↗

Swimming performance traits of twenty-one Australian fish species: a fish passage management tool for use in modified freshwater systems

Freshwater ecosystems have been severely fragmented by artificial in-stream structures designed to manage water for human use. Significant efforts have been made to reconnect freshwater systems for fish movement, through the design and installation of dedicated fish passage structures (fishways) and by incorporating fish-sensitive design features into conventional infrastructure (e.g. culverts). Key to the success of these structures is making sure that the water velocities within them do not exceed the swimming capacities of the local fish species. Swimming performance data is scarce for Australian fish, which have a reduced swimming capacity when compared to many North American and European species. To help close this knowledge gap and assist fisheries management and civil engineering, we report the swimming performance capacities of twenty-one small-bodied fish and juveniles (< 10 cm) of large bodied species native to Australia as measured by critical swimming speed (Ucrit) and burst swimming speed (Usprint) in a recirculating flume. This data is complemented by endurance swim trials in a 12-meter hydraulic flume channel, and by measures of flume traverse success. Building on the utility of this dataset, we used a panel of morphological, behavioural and ecological traits to first assess their relative contributions to the observed swimming performance data, and second, to determine if they could be used to predict swimming performance capacity - a useful tool to assist in the management of species of conservation concern where access to swimming performance data may be limited. We found that body length combined with depth station (benthic, pelagic or surface) explained most of the interspecific variation in observed swimming performance data, followed by body shape and tail shape. These three traits were the most effective at predicting swimming performance in a model/unknown fish. This data will assist civil engineers and fisheries managers in Australia to mitigate the impact of in-stream structures on local fish populations.

zoology↗

Reconstructing lost BOLD signal in individual participants using deep machine learning

The blood oxygen level-dependent (BOLD) signal in functional neuroimaging suffers from magnetic susceptibility artifacts and interference from metal implants. The resulting signal loss hampers functional neuroimaging studies and can lead to misinterpretation of findings. Here, we reconstructed compromised BOLD signal using deep machine learning. We trained a deep learning model to learn principles governing BOLD activity in one dataset and reconstructed artificially-compromised regions in another dataset, frame by frame. Strikingly, BOLD time series extracted from reconstructed frames were correlated with the original time series, even though the frames did not independently carry information about BOLD fluctuations through time. Moreover, reconstructed functional connectivity (FC) maps exhibited good correspondence with the original FC maps, indicating that the deep learning model recovered functional relationships among brain regions. We replicated this result in patients whose scans suffered signal loss due to intracortical electrodes. Critically, the reconstructions captured individual-specific information rather than group information learned during training. Deep machine learning thus presents a unique opportunity to reconstruct compromised BOLD signal while capturing features of an individuals own functional brain organization.

neuroscience↗

A systems approach delivers a functional microRNA catalog and expanded targets for seizure suppression in temporal lobe epilepsy

MicroRNAs (miRNAs) are short noncoding RNAs that shape the gene expression landscape, including during the pathogenesis of temporal lobe epilepsy (TLE). In order to provide a full catalog of the miRNA changes that happen during experimental TLE, we sequenced Argonaute 2-loaded miRNAs in the hippocampus of three different animal models at regular intervals between the time of the initial precipitating insult to the establishment of spontaneous recurrent seizures. The commonly upregulated miRNAs were selected for a functional in vivo screen using oligonucleotide inhibitors. This revealed anti-seizure phenotypes upon inhibition of miR-10a-5p, miR-21a-5p and miR-142a-5p as well as neuroprotection-only effects for inhibition of miR-27a-3p and miR-431-5p. Proteomic data and pathway analysis on predicted and validated targets of these miRNAs indicated a role for TGF{beta} signaling in a shared seizure-modifying mechanism. Together, these results identify functional miRNAs in the hippocampus and a pipeline of new targets for seizure control in epilepsy.

neuroscience↗

Bicistronic expression and differential localization of proteins in insect cells and Drosophila suzukii using picornaviral 2A peptides

Polycistronic expression systems in insects can be used for applications such as recombinant protein production in cells, enhanced transgenesis methods, and the development of novel pest-control strategies based on the sterile insect technique (SIT). Here we tested the performance of four picornaviral 2A self-cleaving peptides (TaV-2A, DrosCV-2A, FMDV 2A1/31 and FMDV 2A1/32) for the co-expression and differential subcellular targeting of two fluorescent marker proteins in cell lines (Anastrepha suspensa AsE01 and Drosophila melanogaster S2 cells) and in vivo in the pest insect Drosophila suzukii. We found that all four 2A peptides showed comparable activity in cell lines, leading to the production of independent upstream and downstream proteins that were directed to the nucleus or membrane by a C-terminal nuclear localization signal (NLS) on the upstream protein and a poly-lysine/CAAX membrane anchor on the downstream protein. Two of the 2A peptides were inserted into piggyBac constructs to create transgenic D. suzukii strains, confirming efficient ribosomal skipping in vivo. Interestingly, we found that the EGFP-CAAX protein was distributed homogeneously in the membrane whereas the DsRed-CAAX protein formed clumps and aggregates that induced extensive membrane blebbing. Accordingly, only flies expressing the EGFP-CAAX protein could be bred to homozygosity whereas the DsRed-CAAX construct was lethal in the homozygous state. Our results therefore demonstrate that four different 2A constructs and two novel targeting motifs are functional in D. suzukii, and that DsRed-CAAX shows dosage-dependent lethality. These molecular elements could be further used to improve expression systems in insects and generate novel pest control strains.\n\nHighlightsO_LIFour picornaviral 2A peptides have been studied for their self-cleaving ability in cell lines and in vivo in the pest insect Drosophila suzukii.\nC_LIO_LIAll tested 2A peptides showed comparable activity that resulted in the production of independent upstream and downstream proteins.\nC_LIO_LIThe proteins co-expressed by 2A peptides were either directed to the cell nucleus by a C-terminal nuclear localization signal (NLS), or to the cell membrane by a poly-lysine/CAAX membrane anchor.\nC_LIO_LIThe combination of optimized membrane localization signals fused to DsRed generated an intrinsically lethal phenotype, which can be used to develop novel pest control strains.\nC_LI

bioengineering↗

Correlated evolution of large DNA fragments in the chromatin interaction network: a case study in Arabidopsis thaliana

In eukaryotes, the three-dimensional (3D) conformation of the genome is far from random, and this nonrandom chromatin organization is strongly correlated with gene expression and protein function, which are two critical determinants of the selective constraints and evolutionary rates of genes. However, whether genes and other elements that are located close to each other in the 3D genome evolve in a coordinated way has not been investigated in any organism. To address this question, we constructed chromatin interaction networks (CINs) in Arabidopsis thaliana based on high-throughput chromosome conformation capture (Hi-C) data and demonstrated that adjacent large DNA fragments in the CIN indeed exhibit more similar levels of polymorphism and evolutionary rates than random fragment pairs. Using simulations that account for the linear distance between fragments, we proved that the 3D chromosomal organization plays a role in the observed correlated evolution. Spatially interacting fragments also exhibit more similar mutation rates and functional constraints in both coding and noncoding regions than the random expectations, indicating that the correlated evolution between 3D neighbors is a result of combined evolutionary forces. A collection of 39 genomic and epigenomic features can explain much of the variance in genetic diversity and evolutionary rates across the genome. Moreover, features that have a greater effect on the evolution of regional sequences tend to show higher similarity between neighboring fragments in the CIN, suggesting a pivotal role of epigenetic modifications and chromatin organization in determining the correlated evolution of large DNA fragments in the 3D genome.

evolutionary biology↗

Unexpected Complexity Of Everyday Manual Behaviors

AO_SCPLOWBSTRACTC_SCPLOWHow does the brain control an effector as complex and versatile as the hand? One possibility is that the neural control of the hand is simplified by limiting the space of achievable hand postures. Indeed, hand kinematics can be largely accounted for within a small subspace of postures. This oft replicated finding has been interpreted as evidence that hand postures are confined to this subspace, and that leaving it volitionally is impossible. A prediction from this hypothesis is that measured hand movements that fall outside of this subspace reflect motor or measurement noise. To address this question, we track hand postures of human participants as they perform two distinct tasks - grasping and signing in American Sign Language. We then apply a standard dimensionality reduction technique - principal components analysis - and replicate the finding that hand movements can be largely described within a reduced subspace. However, we show that postural dimensions that fall outside of this subspace are highly structured and task dependent, suggesting that they too are under volitional control. We conclude that hand control occupies a higher dimensional space than previously considered, and propose that controlling the complexity of hand movements is well within the scope of the brains computational power.

neuroscience↗

Toward Broad Spectrum DHFR inhibitors Targeting Trimethoprim Resistant Enzymes Identified in Clinical Isolates of Methicillin-Resistant Staphylococcus aureus

The spread of plasmid borne resistance enzymes in clinical Staphylococcus aureus isolates is rendering trimethoprim and iclaprim, both inhibitors of dihydrofolate reductase (DHFR), ineffective. Continued exploitation of these targets will require compounds that can broadly inhibit these resistance-confering isoforms. Using a structure-based approach, we have developed a novel class of ionized non-classical antifolates (INCAs) that capture the molecular interactions that have been exclusive to classical antifolates. These modifications allow for a greatly expanded spectrum of activity across these pathogenic DHFR isoforms, while maintaining the ability to penetrate the bacterial cell wall. Using biochemical, structural and computational methods, we are able to optimize these inhibitors to the conserved active sites of the endogenous and trimethoprim resistant DHFR enzymes. Here, we report a series of INCA compounds that exhibit low nanomolar enzymatic activity and potent cellular activity with human selectivity against a panel of clinically relevant TMPR MRSA isolates.

biochemistry↗

Variation in PU.1 binding and chromatin looping at neutrophil enhancers influences autoimmune disease susceptibility

Neutrophils play fundamental roles in innate inflammatory response, shape adaptive immunity1, and have been identified as a potentially causal cell type underpinning genetic associations with immune system traits and diseases2,3 The majority of these variants are non-coding and the underlying mechanisms are not fully understood. Here, we profiled the binding of one of the principal myeloid transcriptional regulators, PU.1, in primary neutrophils across nearly a hundred volunteers, and elucidate the coordinated genetic effects of PU.1 binding variation, local chromatin state, promoter-enhancer interactions and gene expression. We show that PU.1 binding and the associated chain of molecular changes underlie genetically-driven differences in cell count and autoimmune disease susceptibility. Our results advance interpretation for genetic loci associated with neutrophil biology and immune disease.

genetics↗

An oligomeric state-dependent switch in FICD regulates AMPylation and deAMPylation of the chaperone BiP

AMPylation is an inactivating modification that matches the activity of the major endoplasmic reticulum (ER) chaperone BiP to the burden of unfolded proteins. A single ER-localised Fic protein, FICD (HYPE), catalyses both AMPylation and deAMPylation of BiP. However, the basis for the switch in FICDs activity is unknown. We report on the transition of FICD from a dimeric enzyme, that deAMPylates BiP, to a monomer with potent AMPylation activity. Mutations in the dimer interface or in residues tracing an inhibitory relay from the dimer interface to the enzymes active site favour BiP AMPylation in vitro and in cells. Mechanistically, monomerisation relieves a repressive effect allosterically-propagated from the dimer interface to the inhibitory Glu234, thereby permitting AMPylation-competent binding of MgATP. Whereas, a reciprocal signal propagated from the nucleotide binding site, provides a mechanism for coupling the oligomeric-state and enzymatic activity of FICD to the energy status of the ER.\n\nImpact StatementUnique amongst known chaperones, the endoplasmic reticulum (ER)-localized Hsp70, BiP, is subject to transient inactivation under conditions of low ER stress by reversible, covalent modification - AMPylation. The enzyme responsible for this modification, FICD, is in fact a bifunctional enzyme with a single active site capable of both AMPylation and deAMPylation. Here we elucidate, by biochemical, biophysical and structural means, the mechanism by which this enzyme is able to switch enzymatic modality: by regulation of its oligomeric state. The oligomeric state-dependent reciprocal regulation of FICD activity is, in turn, sensitive to the ATP/ADP ratio. This allosteric pathway potentially facilitates the sensing of unfolded protein load in the ER and permits the transduction of this signal into a post-translational buffering of ER chaperone activity.

biochemistry↗

Low-background Acyl-biotinyl Exchange Largely Eliminates the Co-isolation of Non-S-acylated Proteins and Enables Deep S-acylproteomic Analysis

Protein S-acylation (also called palmitoylation) is a common post-translational modification whose deregulation plays a key role in the pathogenesis of many diseases. Acyl-biotinyl exchange (ABE), a widely used method for the enrichment of S-acylated proteins, has the potential of capturing the entire S-acylproteome in any types of biological samples. Here, we showed that current ABE methods suffer from high background arising from the co-isolation of non-S-acylated proteins. The background can be substantially reduced by an additional blockage of residual free cysteine residues with 2,2-dithiodipyridine prior to biotin-HPDP reaction. Coupling the low-background ABE (LB-ABE) method with label-free quantitative proteomics, 2,895 high-confidence candidate S-acylated proteins (including 1,591 known S-acylated proteins) were identified from human prostate cancer LNCaP cells, representing so-far the largest S-acylproteome dataset identified in a single study. Immunoblotting analysis confirmed the S-acylation of five known and five novel prostate cancer-related S-acylated proteins in LNCaP cells and suggested that their S-acylation levels were about 0.6-1.8%. In summary, the LB-ABE method largely eliminates the co-isolation of non-S-acylated proteins and enables deep S-acylproteomic analysis. It is expected to facilitate much more comprehensive and accurate quantification of S-acylproteomes than previous ABE methods.

biochemistry↗

Robust network inference using response logic

MotivationA major challenge in molecular and cellular biology is to map out the regulatory networks of cells. As regulatory interactions can typically not be directly observed experimentally, various computational methods have been proposed to disentangling direct and indirect effects. Most of these rely on assumptions that are rarely met or cannot be adapted to a given context. ResultsWe present a network inference method that is based on a simple response logic with minimal presumptions. It requires that we can experimentally observe whether or not some of the systems components respond to perturbations of some other components, and then identifies the directed networks that most accurately account for the observed propagation of the signal. To cope with the intractable number of possible networks, we developed a logic programming approach that can infer networks of hundreds of nodes, while being robust to noisy, heterogeneous or missing data. This allows to directly integrate prior network knowledge and additional constraints such as sparsity. We systematically benchmark our method on KEGG pathways, and show that it outperforms existing approaches in DREAM3 and DREAM4-challenges. Applied to a perturbation data set on PI3K and MAPK pathways in isogenic models of a colon cancer cell line, it generates plausible network hypotheses that explain distinct sensitivities towards EGFR inhibitors by different PI3K mutants. Availability and ImplementationA Python/Answer Set Programming implementation can be accessed at github.com/GrossTor/response-logic. Contactnils.bluethgen@charite.de

systems biology↗

Temporal modulation of host aerobic glycolysis determines the outcome of M. marinum infection

Macrophages are the first-line host defense where the invading Mycobacterium tuberculosis (Mtb) encounters. It has been recently reported that host aerobic glycolysis was elevated post the infection by a couple of virulent mycobacterial species. However, whether this metabolic transition is required for host defense against intracellular pathogens and the underlying mechanisms remain to be further investigated. By analyzing carbon metabolism, we found that macrophages infected by M. marinum, a surrogate mycobacterial specie to Mtb, showed a strong elevation of glycolysis. Next, three glycolysis inhibitors were examined for their ability to inhibit mycobacterial proliferation inside RAW264.7, a murine macrophage-like cell line. Among them, a glucose analog, 2-deoxyglucose (2-DG) displayed a protective effect on assisting host to resist mycobacterial infection, which was further validated in zebrafish-infection model. The phagocytosis of M. marinum was significantly decreased in macrophages pre-treated with 2-DG at concentrations of 0.5 and 1 mM, at which no inhibitory effect was posed on M. marinum growth in vitro. Moreover, 2-DG pre-treatment exerted a significant protective effect on zebrafish larvae to limit the proliferation of M. marinum, and such effect was correlated to tumor necrosis factor alpha (TNF-). On the contrary, the 2-DG treatment post infection did not restrain proliferation of M. marinum in WT zebrafish, and even accelerated bacterial replication in TNF--/- zebrafish. Together, modulation of glycolysis prior to infection boosts host immunity against M. marinum infection, indicating a potential intervention strategy to control mycobacterial infection.\n\nAuthor SummaryAs an intracellular pathogen, Mtb exploits multiple strategies to invade and hijack macrophages for its own advantages. Accordingly, recent investigations have shown that Mtb infection is accompanied with an alteration of host glucose metabolism. Macrophage and zebrafish infection models of M. marinum, facilitating our understanding towards mycobacterial pathogenesis, were applied in this study. We found that the pre-treatment of macrophages with a glucose analog, 2-DG, inhibited aerobic glycolysis and made host cells more inert to phagocytose the bud. In infected zebrafish larvae, bacterial load inside host pretreated with 2-DG remains at a significantly lower level compared to the untreated group. These findings imply that the modulation of host glycolysis regulates the fate of M. marinum infection, and indicate a promising metabolic target in TB intervention.

microbiology↗

Migration of gastric cancer is suppressed by rabies virus glycoprotein via regulating α7-nicotinic acetylcholine receptors/ERK-EMT

Nicotinic acetylcholine receptors (nAChRs) have been reported to be overexpressed in malignancies in humans and is associated with tumorigenesis and cell migration. In previous studies of gastric cancer, alpha7 nicotinic acetylcholine receptor (7-nAChR) overexpression can induce epithelial-mesenchymal transition (EMT) and promote migration of gastric cancer cells. Recombinant avirulent Newcastle disease virus (NDV) LaSota strain expressing the rabies virus glycoprotein (rL-RVG) may promote apoptosis of gastric cancer cells and reduces migration of lung cancer metastasis. However, whether rL-RVG inhibits migration of gastric cancer cells and what the underlying functional mechanism is remains unknown. In this study, our findings demonstrate that rL-RVG suppressed migration and reduced EMT of gastric cancer cells via 7-nAChR in vitro. Furthermore rL-RVG decreased the phosphorylation levels of the MEK/ERK signaling pathway such as down-regulating the expression of P-MEK and P-ERK. Additionally, rL-RVG also reduced the expression level of mesenchymal markers N-cadherin and Vimentin and enhanced the expression of the epithelial marker E-cadherin. Lastly, rL-RVG together with nicotinic acetylcholine receptors (nAChRs) inhibited gastric cancer epithelial to mesenchymal transition (EMT) which suppressed gastric cancer cell migration. We also found that rL-RVG suppresses the growth of gastric cancer subcutaneous tumor cells in vivo. Thus, rL-RVG inhibits 7-nAChR-MEK/ERK-EMT to suppress migration of gastric cancer cells.

cancer biology↗

FDA-ARGOS: A Public Quality-Controlled Genome Database Resource for Infectious Disease Sequencing Diagnostics and Regulatory Science Research

Infectious disease next generation sequencing (ID-NGS) diagnostics are on the cusp of revolutionizing the clinical market. To facilitate this transition, FDA proactively invested in tools to support innovation of emerging technologies. FDA and collaborators established a publicly available database, FDA dAtabase for Regulatory-Grade micrObial Sequences (FDA-ARGOS), as a tool to fill reference database gaps with quality-controlled genomes. This manuscript discusses quality control metrics for the proposed FDA-ARGOS genomic resource and outlines the need for quality-controlled genome gap filling in the public domain. Here, we also present three case studies showcasing potential applications for FDA-ARGOS in infectious disease diagnostics, specifically: assay design, reference database and in silico sequence comparison in combination with representative microbial organism wet lab testing; a novel composite validation strategy for ID-NGS diagnostics. The use of FDA-ARGOS as an in silico comparator tool could reduce the burden for completing ID-NGS clinical trials. In addition, use cases identifying Enterococcus avium and Ebola virus (Zaire ebolavirus variant Makona) demonstrate the utility of FDA-ARGOS as a reference database for independent performance validation of new tests and for documenting how one would use this database as an in silico sequence target comparator tool for ID-NGS validation, respectively.

microbiology↗

Mesenchymal stem cell derived exosomes enhance lymphangiogenesis via exosomal transfer of Ang-2/Tie2

Mesenchymal stem cell derived exosomes (MSC-Ex) are nanosized membrane-bound extracellular vesicles found in MSC conditioned medium, that have yielded beneficial effects in several experimental models of organ injury. However, the therapeutic value and mechanism of MSC-Ex in lymphedema is poorly understood. Here we find that human umbilical cord MSCs derived exosomes (hucMSC-Ex) treatment contributed to the regeneration of LYVE-1 positive lymphatic vessels and reduction of lymphedema in a mouse model of tail lymphedema. Following uptake, exosomal lymphangiogenic factors (angiopoietin (Ang)-2 and Tie2) are taken up by HDLECs and promoted HDLECs proliferation, migration, and tube formation in vitro. We also find that exosomal Ang-2 and Tie2 exert a prolymphangiogenic effect on HDLECs through upregulating Prox1 and VEGFR3/p-Akt expression. In conclusion, our result unravel a previously unappreciated prolymphangiogenic role of hucMSC-Ex in lymphedema therapy and provide a new mechanism of Ang-2 in therapeutic lymphangiogenesis.

bioengineering↗

Drosophila scribble mutant tumors undergo a transition from a growth arrest state to a proliferative state over time

The Drosophila neoplastic tumor suppressor gene (nTSG) mutant tumors have successfully modeled many aspects of human tumor progression. However, the fly nTSG mutant tumors progress rapidly over days. This is in contrast with most human tumors which develop slowly, harbor heterogeneous cell populations for selection and undergo an evolution-like process. Whether the fast-growing fly nTSG mutant tumors have capacity for evolution remains unclear. Through quantitative analysis of the scrib mutant tumor growth, we found that the scrib mutant tumors evolve to display different growth rates and cell cycle profiles over time. Multiple growth-regulatory signaling pathways show quantitative differences in early versus late scrib mutant tumors. These data suggest that the scrib mutant tumors undergo a transition from a growth arrest state to a proliferative state. Through longitudinal single cell RNA (scRNA) data analysis we found that the scrib mutant tumors harbor heterogeneous cell populations likely of distinct proliferative states, which are available for potential selection. This study raises the possibility of studying tumor evolution in a genetically accessible and fast-growing invertebrate tumor model.

developmental biology↗