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Sun, T.

Publications and source records attributed to Sun, T..

At least 55 records · Page 3Linked to original sources

Absorbing molecules make both abdomen and back transparent in live mice

The field of tissue clearing has experienced rapid advancements in the past decades. Tissue clearing techniques primarily rely on physical or chemical approaches to match the refractive indices of cells and their surrounding medium, thereby reducing light scattering and rendering the tissue optically transparent. By doing so, it becomes possible to utilize fluorescence imaging and 3D reconstruction techniques to observe and analyze the contents and structures of tissues at a cellular level. However, effective research on in vivo tissue clearing remains limited due to the involvement of toxic substances and the removal of water or lipids. A recent article in Science reports a technique that achieves tissue transparency in live animals with absorbing molecules, marking a significant advancement in the field of in vivo tissue clearing. Although this work has great potential for imaging and light-based therapeutics, some labs found it difficult to reproduce the reported results. In this study, we report the successful reproduction of the findings, provide experimental details that we identified as key to reproducibility, present a new transparency effect observed in the back of live mice, which was not shown in the original paper, and offer insights into the future development and applications of in vivo clearing reagents.

bioengineering↗

Epigenetic derepression of H3K9me3 mitigates Alzheimer-related pathology and improves cognition via immunomodulation and Vgf induction

We investigated the role of histone 3 lysine 9 trimethylation (H3K9me3), an epigenetic mechanism involved in the repression of synaptic plasticity and memory-related genes, within aging and Alzheimers disease (AD). Our study reveals that elevated cortical H3K9me3 strongly correlates with cognitive dysfunction in individuals with mild cognitive impairment (MCI) and AD. In old (18 months) and younger (14 months) APPSWE/PS1{Delta}E9 and 3xTg AD mouse models, inhibiting SUV39H1 methyltransferase with ETP69, substantially reduces cerebral H3K9me3 levels and attenuates amyloid-{beta} burden, tau pathology, and gliosis. Administration of ETP69 further promotes dendritic spine formation, leading to rapid and sustained improvements in cognitive function. Proteomics analysis indicates that a significant proportion of dysregulated proteins in the brains of AD-model mice are reversed by ETP69. These proteins are enriched for synaptic plasticity and learning-related pathways. ETP69 exerts its effects through multiple neuroprotective mechanisms, including regulation of neuroinflammation, induction of both blood and cerebral-infiltrating monocytes involved in cerebral A{beta} clearance. Moreover, ETP69 activates brain-derived neurotrophic factor (Bdnf) network, and particularly its downstream effector neurosecretory protein Vgf. These findings support the pharmacological inhibition of H3K9me3-mediated gene silencing to reverse AD-related pathology and cognitive decline.

neuroscience↗

Making Aptamers More Antibody-like: Targeting AXL in Vivo Using a Bottlebrush Polymer-Conjugated Aptamer

The overexpression of receptor tyrosine kinase AXL is linked to acquired drug resistance in cancer treatments. Aptamers, acting as antibody surrogates, have been envisioned as potential inhibitors for AXL. However, aptamers face difficult pharmacological challenges including rapid degradation and clearance. Herein, we report a phosphodiester-backboned bottlebrush polymer as a carrier for conjugated aptamers. Termed pacDNA, the conjugate improves aptamer specificity in vivo, prolongs blood retention, and enhances overall aptamer bioactivity. Treatment with pacDNA in AXL-overexpressing cell lines significantly inhibits AXL phosphorylation, resulting in reduced cancer cell migration and invasion. In a non-small cell lung cancer xenograft model (NCI-H1299), pacDNA treatment leads to single-agent reduction in tumor growth. These results highlight the potential of bottlebrush polymers in the field of aptamer therapeutics.

cancer biology↗

Bottlebrush polymers with sequence-controlled backbones for enhanced oligonucleotide delivery

The clinical translation of oligonucleotide-based thera-peutics continues to encounter challenges in delivery. In this study, we introduce a novel class of delivery vehicles for oligonucleotides, which are based on polyethylene glycol (PEG) bottlebrush polymers with sequence-defined backbones. Using solid-phase synthesis and bespoke phosphoramidites, the oligonucleotide and the polymer backbone can both be assembled on the solid support. The synthesis allows chemical modifiers such as carbon 18 (C18) units to be incorporated into the backbone in specific patterns to modulate the cell-materials interactions. Subsequently, PEG side chains were grafted onto the polymer segment of the resulting polymer-oligonucleotide conjugate, yielding bottlebrush polymers. We report an optimal pattern of the C18 modifier that leads to improved cellular uptake, plasma phar-macokinetics, biodistribution, and antisense activity in vivo. Our results provide valuable insights into the pacDNA structure-property relationship and suggest a possibility of tuning the polymer backbone to meet the specific delivery requirements of various diseases. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=166 SRC="FIGDIR/small/616318v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@1a332e7org.highwire.dtl.DTLVardef@1630ab1org.highwire.dtl.DTLVardef@15306dforg.highwire.dtl.DTLVardef@1e83f0e_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

Genome-wide A to G and C to T Mutations Induced by Functional TadA Variants in Escherichia coli

The fusion expression of DNA replication-related proteins with nucleotide deaminase enzymes promotes random mutations in bacterial genomes, thereby increasing genetic diversity among population. Most previous studies have focused on cytosine deaminase, which produces only C[->]T mutations, significantly limiting the variety of mutation types. In this study, we developed a fusion expression system by combining DnaG (RNA primase) with adenine deaminase TadA-8e (DnaG-TadA) in Escherichia coli, which is capable of rapidly introducing A[->]G mutations into the E. coli genome, resulting in a 664-fold increase in terms of mutation rate. Additionally, we engineered a dual-functional TadA variant, TadAD, and then fused it with DnaG. This construct introduced both C[->]T and A[->]G mutations into the E. coli genome, with the mutation rate further increased by 370-fold upon co-expression with an uracil glycosylase inhibitor (DnaG-TadAD-UGI). We applied DnaG-TadA and DnaG-TadAD-UGI systems to the adaptive laboratory evolution for Cd2+ and kanamycin resistance, achieving an 8.0 mM Cd2+ and 200 g/mL kanamycin tolerance within just 17 days and 132 hours, respectively. Compared to conventional evolution methods, the final tolerance levels were increased by 320% and 266%, respectively. Our work offers a novel strategy for random mutagenesis in E. coli and potentially other prokaryotic species. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=98 SRC="FIGDIR/small/610230v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@176e445org.highwire.dtl.DTLVardef@848b7corg.highwire.dtl.DTLVardef@1e190b9org.highwire.dtl.DTLVardef@1e47b44_HPS_FORMAT_FIGEXP M_FIG C_FIG For TOC only

synthetic biology↗

Enhanced Salt Tolerance in Synechocystis sp. PCC 6803 Through Adaptive Evolution: Mechanisms and Applications for Environmental Bioremediation

Salt stress is common in natural environments, where elevated salt levels in brackish water and saline soil can hinder the growth of organisms, thereby exacerbating environmental challenges. Developing salt-tolerant organisms not only uncovers novel mechanisms of salt tolerance but also lays the groundwork for managing and utilizing saline environments. Cyanobacteria, which are widely distributed in hydrosphere and soil, serve as ideal models for studying salt stress. In this study, the model cyanobacterium Synechocystis sp. PCC 6803 was selected, whose salt (NaCl) tolerance improved from 4.0% to 6.5% (m/v) through adaptive laboratory evolution. Genome re-sequencing and mutant analysis identified six key genes associated with salt tolerance. Notably, the deletion of slr1670, which encodes glycerol glucoside hydrolase, improved the strains salt tolerance. In addition, slr1753 encodes a membrane protein that may enhance salt tolerance by facilitating ion transport to the extracellular space. Further analysis revealed that overexpression of slr1753 significantly accumulates Na+ on the cell surface, enabling effective seawater treatment using the engineered strain, resulting in a 6.35% reduction of Na+ in the seawater. Moreover, the adapted bacteria can be used for the remediation of saline soil samples, leading to a 184.2% and 43.8% increase in the germination rate and average height of Brassica rapa chinensis, respectively, along with a 25.3% rise in total organic carbon content and reductions in both total salt content by 1.82% and pH by 1.91% in soil. This study provides novel insights into salt tolerance mechanisms and the bioremediation of high-salinity environments. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC="FIGDIR/small/610226v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@cde16aorg.highwire.dtl.DTLVardef@8a27ccorg.highwire.dtl.DTLVardef@3af9bforg.highwire.dtl.DTLVardef@1e29cfb_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

Expression and characterization of the complete cyanophage genome PP in the heterologous host Synechococcus elongatus PCC 7942

Cyanophages are considered a promising biological management option for treating cyanobacterial blooms. Broadening the host range of cyanophages and/or shortening the lysis cycle by designing and synthesizing artificial cyanophages are potential strategies to enhance their effectiveness and efficiency. However, the rescue of artificial cyanophage genomes remains unexplored. In this study, we achieved the integration of a full-length cyanophage genome, PP, which originally infects Plectonema boryanum FACHB-240, into the model cyanobacterium Synechococcus elongatus PCC 7942. Since the integration of these large fragments ([~]42 kb) into cyanobacteria depended on conjugation via Escherichia coli, the toxic open reading frames (ORFs) of PP to E. coli were first identified, leading to the identification of toxic ORF6, ORF11, and ORF22. The original PP genome was then rearranged, and the three toxic ORFs were controlled using a tandem induction switch. The full length of the PP genome was integrated into the genome of S. elongatus PCC 7942 via two rounds of homologous recombination. Interestingly, compared to the control strain, the integration of the PP genome decreased photosynthesis and carbon fixation in S. elongatus PCC 7942, exhibiting cyanophage-like behavior. Transcriptomic analysis revealed that 32 of the 41 ORFs of the PP genome were transcribed in S. elongatus PCC 7942, significantly altering the energy metabolism and carbon fixation pathways. These influences were further demonstrated using metabolomics. This study provides a comprehensive approach for the artificial design and integration of cyanophage genomes in cyanobacteria, laying the foundation for their real rescue in the future.

synthetic biology↗

Systematic Evaluation of Cell Type Deconvolution Methods for Plasma Cell-free DNA

Plasma cell-free DNA (cfDNA) is derived from cellular death in various tissues. Investigating the origin of cfDNA through tissue/cell type deconvolution allows us to detect changes in tissue homeostasis that occur during disease progression or in response to treatment. Consequently, cfDNA has emerged as a valuable noninvasive biomarker for disease detection and treatment monitoring. Although there are numerous methylation-based methods of cfDNA cell type deconvolution available, a comprehensive and systematic evaluation of these methods has yet to be conducted. In this study, we thoroughly benchmarked five previously published methods: MethAtlas, cfNOMe, CelFiE, CelFEER, and UXM. Utilizing deep whole-genome bisulfite sequencing data from 35 human cell types, we generated cfDNA mixtures with known ground truth to assess the deconvolution performance under various scenarios. Our findings indicate that different factors, including sequencing depth, reference marker selection, and reference completeness, influence cell type deconvolution performance. Notably, omitting cell types present in a mixture from the reference leads to suboptimal results. Despite each method exhibited distinct performances under various scenarios, CelFEER and UXM exhibit overall superior performance compared to the others. In summary, we comprehensively evaluated factors influencing methylation-based cfDNA cell type deconvolution and proposed general guidelines to maximize the performance.

bioinformatics↗

Catalytically inactive SHP1-C453S mutant gain of "robust LLPS" function

SHP1 is a non-receptor protein tyrosine phosphatase extensively expressed in hematopoietic cells, exerting a pivotal role as an immunosuppressive factor. Our previous studies have suggested that SHP1 can undergo liquid-liquid phase separation (LLPS). In this study, the SHP1-C455S mutant, commonly utilized in biochemical assays due to its lack of catalytic phosphatase activity, unexpectedly exhibited a remarkably robust ability for LLPS. Since the C453S mutation has been previously shown to potentially induce a conformational transition of SHP1 from a closed to an open state, we hypothesize that the enhanced LLPS capability of SHP1 may be facilitated by this conformational alteration. The SHP1-C453S mutant exhibited robust LLPS activity, while completely abrogating its phosphatase activity. This allows for effective investigation of the catalytic activity and LLPS capability of SHP1.

molecular biology↗

Screening of associated bacteria of Alexandrium catenella on affecting PSTs production and influence mechanism

Alexandrium causes serious food safety and human death due to paralytic shellfish toxins (PSTs) production. The associated bacteria can affect PSTs production of Alexandrium. However, the influencing mechanism is still unclear. Here we firstly screened functional associated bacteria for affecting PSTs production of Alexandrium catenella in Yangtze Estuary and further studied their influence on physiological process and molecular regulation of A. catenella. Thirteen bacteria strains for affecting PSTs production of A. catenella were selected. The A. catenella strains co-cultured with different functional associated bacteria all produced more PSTs than axenic strain with antibiotic treatment. Compared with axenic A. catenella, the non-axenic A. catenella produced more algal cells, soluble sugar, soluble protein and neutral lipid. By RNA-seq, it was found that non-axenic A. catenella produced more upregulated functional genes than axenic A. catenella. The biosynthesis of cofactors and spliceosome were the dominant different pathways between axenic and non-axenic A. catenella strains. The sxtA expression was closely related with Arginine and proline metabolism, Arginine biosynthesis, Fatty acid biosynthesis, TCA cycle and Glutathione metabolism, which were all downregulated in axenic A. catenella. Meantime, the non-axenic A. catenella under nitrogen deprivation produced less PSTs and functional genes than non-axenic strain under common culture condition, indicating the nitrogen significance for PSTs production. The detailed signal molecular released by associated bacteria for regulating PSTs of A. catenella needs to be further studied.

ecology↗

Battery-Free Optoelectronic Patch for Photodynamic and Light Therapies in Treating Bacteria-Infected Wounds

Light therapy is an effective approach for the treatment of a variety of challenging dermatological conditions. In contrast to existing methods involving high doses and large areas of illumination, alternative strategies based on wearable designs that utilize a low light dose over an extended period provide a precise and convenient treatment. In this study, we present a battery-free, skin-integrated optoelectronic patch that incorporates a coil-powered circuit, an array of microscale violet and red light emitting diodes (LEDs), and polymer microneedles (MNs) loaded with 5-aminolevulinic acid (5-ALA). This polymer MNs, based on the biodegradable composite materials of polyvinyl alcohol (PVA) and hyaluronic acid (HA), serves as light waveguides for optical access and a medium for drug release into deeper skin layers. Unlike conventional clinical photomedical appliances with a rigid and fixed light source, this flexible design allows for a conformable light source that can be applied directly to the skin. In animal models with bacterial-infected wounds, the experimental group with the combination treatment of metronomic photodynamic and light therapies reduced 2.48 log10 CFU mL-1 in bactericidal level compared to the control group, indicating an effective anti-infective response. Furthermore, post-treatment analysis revealed the activation of proregenerative genes in monocyte and macrophage cell populations, suggesting enhanced tissue regeneration, neovascularization, and dermal recovery. Overall, this optoelectronic patch design broadens the scope for targeting deep skin lesions, and provides an alternative with the functionality of standard clinical light therapy methods.

bioengineering↗

Oligodendrocytes and neurons contribute to amyloid-β deposition in Alzheimer's disease

In Alzheimers disease (AD), amyloid-{beta} (A{beta}) is thought to be of neuronal origin. However, in single-cell RNAseq datasets from mouse and human, we found transcripts of amyloid precursor protein (APP) and the amyloidogenic-processing machinery equally abundant in oligodendrocytes (OLs). By cell-type-specific deletion of Bace1 in a humanized knock-in AD model, APPNLGF, we demonstrate that almost a third of cortical A{beta} deposited in plaques is derived from OLs. However, excitatory projection neurons must provide a threshold level of A{beta} production for plaque deposition to occur and for oligodendroglial A{beta} to co-aggregate. Indeed, very few plaques are deposited in the absence of neuronally-derived A{beta}, although soluble A{beta} species are readily detected, especially in subcortical white matter. Our data identify OLs as a source of A{beta} in vivo and further underscore a non-linear relationship between cellular A{beta} production and resulting plaque formation. Ultimately, our observations are relevant for therapeutic strategies aimed at disease prevention in AD.

neuroscience↗

VirusImmu: a novel ensemble machine learning approach for viral immunogenicity prediction

BackgroundThe viruses threats provoke concerns regarding their sustained epidemic transmission, making the development of vaccines particularly important. In the prolonged and costly process of vaccine development, the most important initial step is to identify protective immunogens. Machine learning (ML) approaches are productive in analyzing big data such as microbial proteomes, and can remarkably reduce the cost of experimental work in developing novel vaccine candidates. ResultsWe intensively evaluated the immunogenicity prediction power of eight commonly-used ML methods by random sampling cross validation on a large dataset consisting of known viral immunogens and non-immunogens we manually curated from the public domain. XGBoost, kNN and RF showed the strongest predictive power. We then proposed a novel soft-voting based ensemble approach (VirusImmu), which demonstrated a powerful and stable capability for viral immunogenicity prediction across the test set and external test set irrespective of protein sequence length. VirusImmu was successfully applied to facilitate identifying linear B cell epitopes against African Swine Fever Virus as confirmed by indirect ELISA in vitro. ConclusionsVirusImmu exhibited tremendous potentials in predicting immunogenicity of viral protein segments. It is freely accessible at https://github.com/zhangjbig/VirusImmu.

bioinformatics↗

Investigating the Impact of Microplastics on Fish Muscle Cell Proliferation and Differentiation: Enhancing Food Safety in Cultivated Meat Production

Cultivated meat, a sustainable alternative to traditional livestock farming, has gained attention for its potential environmental and health benefits. However, concerns about microplastic contamination pose challenges, especially when sourcing cells from marine organisms prone to microplastic bioaccumulation. Additionally, the pervasive presence of microplastics in laboratory settings, ingredients, and during the production, increases the risk of unintentional contamination. This study focused on Atlantic mackerel (Scomber scombrus) skeletal muscle cell lines to examine the effects of microplastic exposure, represented by fluorescent polyethylene microspheres (10-45 {micro}m) on cell performance including cell proliferation, cell viability, gene expression, and differentiation processes critical for cultivated meat production. The results revealed significant impacts on cell attachment and proliferation at microplastic concentrations of 1 {micro}g/mL, 10 {micro}g/mL, and 50 {micro}g/mL. Notably, the 10 {micro}g/mL concentration exerted the most pronounced effects on cell viability during both attachment and proliferation phases. While the results indicated that both microplastic concentration and size influence cell viability, cell differentiation remained unaffected, and additional contributing factors require further investigation. These findings underscore the necessity of thoroughly exploring microplastic-cell interactions to ensure food safety and safeguard health within the burgeoning cultivated meat industry.

systems biology↗

Vitamin D promotes DNase1L3 to degrade ecDNA and inhibit the malignant progression of hepatocellular carcinoma

Extrachromosomal DNA (ecDNA) is an important carrier of oncogene amplification. However, the degradation mechanism of ecDNA is not well understood. We found that endogenous natural molecular vitamin D (VD) reduces ecDNA and inhibits the progression of hepatocellular carcinoma (HCC). VD reduces ecDNA depending on its transporter GC, which interacts with the endonuclease DNase1L3 and stabilize its protein level. DNase1L3 with its lipophilic region on N-terminus exhibiting an affinity towards lipid droplets (LDs) demonstrates direct degradation effect on ecDNA. Intranuclear LDs are abundantly distributed around ecDNA, DNase1L3 therefore shows an affinity for ecDNA owing to its lipophilic region. VD, as a lipid-soluble molecule, can increase the size of LDs and improve the degradation of DNase1L3 on ecDNA. Consequently, we designed two mRNA-based therapeutics, DNase1L3 and GC-DNase, both of which had an anti-tumor effect on PDX models. The above results showed that treatments targeting ecDNA in cancer are prospective in clinical practice.

cancer biology↗

Extended toolboxes enable efficient biosynthesis of valuable chemicals directly from CO2 in fast-growing Synechococcus sp. PCC 11901

CO2 recycle is crucial to the global carbon neutrality. Though cyanobacteria are known to be photoautotrophic cell factories capable of converting CO2 into valuable chemicals, their slower growth rate and lower biomass accumulation compared to those of the heterotrophic organisms significantly restrict their application at commercial scale. The newly discovered marine cyanobacterium, Synechococcus sp. PCC 11901 (hereafter PCC 11901) offers several advantages like rapid growth, high biomass and high salinity tolerance, and could become a new generation of cyanobacterial chassis. To promote its application, in this study we developed genetic toolboxes applicable to PCC11901. First, a cobalamin (VB12)-independent chassis was constructed, allowing for its cheaper cultivation. Second, genome copy numbers and transformation methods were respectively measured and optimized. The 14 neutral sites were identified and characterized within the genome PCC 11901, providing locations for genetic integration of exogenous cassettes. Subsequently, libraries were developed, reaching an expression range of approximately 800 folds for constitutive promoters and an induction fold of up to approximately 400 for inducible promotor, respectively. As a proof of concept of its utilization, we engineered the synthetic pathways of glucosylglycerol (GG) into PCC 11901 using the established toolboxes, yielding 590.41 {+/-} 21.48 mg/L for GG production. Notably, we found the cobalamin-independent PCC 11901 chassis exhibited superior self-sedimentation ability compared to the wild-type chassis. Our work here made it possible to develop the fast-growing PCC 11901 as efficient carbon-neutral cell factory in the future.

synthetic biology↗

Multi-omics analysis reveals critical cis-regulatory roles of transposable elements in livestock genomes

As a major source of genetic and regulatory variation in their host genome, transposable elements (TEs) have gained a growing interest in research on humans and model organisms. In this species, integrative analysis of multi-omics data has shed light on the regulatory functions of TEs. However, there remains a notable gap in our understanding of TEs in domesticated animals. we annotated TEs in the genomes of pigs, cattle, and chickens, respectively, and systematically compared the genome distributions and amplification patterns of TEs across these three species. Furthermore, by integrating multi-tissue RNA-seq, ATAC-seq, and histone modification ChIP-seq data, we explored the expression atlas of TEs and their contribution to cis-regulatory elements (CREs) in different tissues of the three species. Most importantly, we developed a novel computational framework that revealed TE-mediated gene regulatory networks (TE-GRNs) underlying tissue-related biological processes. To demonstrate the power of this approach, we applied our framework to analyze liver tissues across the three different species. Overall, our research provides novel insights into the regulatory functions of TEs in livestock animals and highlights a computational framework to uncover TE-GRNs in various biological contexts.

genomics↗

Proteomic analysis revealed the function of PoElp3 in development, pathogenicity and autophagy through the tRNA-mediated translation efficiency in the rice blast fungus

The Elongator complex is conserved in a wide range of species and plays crucial roles in diverse cellular processes. We have previously shown that the Elongator protein PoELp3 was involved in the asexual development, pathogenicity, and autophagy of the rice blast fungus. In this study, we further revealed that PoElp3 functions via tRNA-mediated protein integrity. Phenotypic analyses revealed that overexpression of two of the tRNAs, tK(UUU) and tQ(UUG) could rescue the defects in {Delta}Poelp3 strain. TMT-based proteomic and transcriptional analyses demonstrated that 386 proteins were down-regulated in {Delta}Poelp3 strain compared with wild type strain Guy11, in a transcription-independent manner. Codon usage assays revealed an enrichment of Glutamine CAA-biased mRNA in the 386 proteins compared with the 70-15 genome. In addition to those reported previously, we also found that PoErp9, a sphingolipid C9-methyltransferase, was down-regulated in the {Delta}Poelp3 strain. Through an ILV2-specific integration of PoERP9-GFP into the wild type and {Delta}Poelp3 strain, we were able to show that PoErp9 was positively regulated by PoElp3 translationally but not transcriptionally. Functional analyses revealed that PoErp9 was involved in the fungal growth, conidial development, pathogenicity, and TOR-related autophagy homeostasis in P. oryzae. Taken together, our results suggested that PoElp3 acts through the tRNA-mediated translational efficiency to regulate asexual development, pathogenicity, and autophagy in the rice blast fungus.

pathology↗