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Liu, T.

Publications and source records attributed to Liu, T..

At least 289 records · Page 16Linked to original sources
bioRxiv2022

Assessment of fish spermatogenesis through high-quality immunofluorescence against fish testicular samples with an antibody set

A complete evaluation of the spermatogenetic status of a fish by accurately identifying different types of spermatogenic cells is useful not only for reproductive studies but also for genetic breeding. For this task, it is required to establish a simple and practical experimental procedure, to obtain repeatable, high-quality imaging data. Here, we have developed antibodies against the zebrafish (Danio rerio) spermatogenesis-related proteins, including Ddx4, Piwil1, Sycp3, and Pcna, and an integrated method for high-quality and high-through output immunofluorescence on testis sections of different fish species. We accurately identified different spermatogenic cells at different stages. Type-A spermatogonia can be identified by the highest expression of Ddx4 and Piwil1 among different spermatogenic cells. Type-B spermatogonia is identified by the second highest expression of Ddx4 and the highest expression of Pcna among different spermatogenic cells. Spermatids can be distinguished from spermatozoa by the expression of Piwil1. The different subtypes of primary spermatocytes (SPC-I) can be identified by co-staining of Sycp3 and Pcna. Leptotene SPC-I show polar expression of both Sycp3 and Pcna at the same side of the nucleus. All the antibodies were tested for practicality in four fish species, Chinese rare minnow (Gobiocypris rarus), common carp (Cyprinus carpio), blunt snout bream (Megalobrama amblycephala), and rice field eel (Monopterus albus). Using this method and the antibody sets, we were able to precisely and accurately evaluate the spermatogenetic status in different fish species. HighlightsO_LIA practical method for high-quality immunofluorescence against fish testicular samples has been developed. C_LIO_LIAn antibody set of Ddx4, Piwil1, Sycp3 and Pcna have been developed for identification of a variety of spermatogenic cells in different fish species. C_LIO_LIAntibodies against zebrafish proteins have been tested in the four fish species, Chinese rare minnow, common carp, blunt snout bream and rice field eel. C_LI

developmental biology↗
bioRxiv2022

Single-cell analysis of non-alcoholic fatty livers identifies a role for the constitutive androstane receptor

Non-alcoholic fatty liver disease is a heterogeneous disease with unclear underlying molecular mechanisms. While several genetic risk factors have been identified, the cellular and molecular heterogeneity associated with the development of hepatic steatosis are still not fully understood. Here, we perform single-cell RNA sequencing of hepatocytes and hepatic nonparenchymal cells to map the lipid signatures in mice with non-alcoholic fatty liver disease (NAFLD). We uncover previously unidentified clusters of hepatocytes characterized by either high or low srebp1 expression with unique molecular signatures of lipid synthesis. We find that NAFLD livers have elevated expression of the constitutive androstane receptor (CAR), a gene previously associated with lipid synthesis. Furthermore, nuclear expression of CAR positively correlates with steatohepatitis in humans. These findings demonstrate significant cellular differences in lipid signatures and identify a gene with a high likelihood of being linked to hepatic steatosis in humans.

cell biology↗
bioRxiv2022

The Spatial Organization of Bacterial Transcriptional Regulatory Networks

Transcriptional regulatory network (TRN) is the central pivot of a prokaryotic organism to receive, process and respond to internal and external environmental information. However, little is known about its spatial organization so far. In recent years, chromatin interaction data of bacteria such as Escherichia coli and Bacillus subtilis have been published, making it possible to study the spatial organization of bacterial transcriptional regulatory networks. By combining TRNs and chromatin interaction data of E. coli and B. subtilis, we explored the spatial organization characteristics of bacterial TRNs in many aspects such as regulation directions (positive and negative), central nodes (hubs, bottlenecks), hierarchical levels (top, middle, bottom) and network motifs (feed-forward loops and single input modules) of the TRNs and found that the bacterial TRNs have a variety of stable spatial organization features under different physiological conditions which may be closely related with basic life activities. Our findings provided new insights into the connection between transcriptional regulation and the spatial organization of chromosome in bacteria, and might serve as a foundation for spatial-distance-based gene circuit design in synthetic biology.

systems biology↗
bioRxiv2022

Viscoelastic Notch Signaling Hydrogel Induces Liver Bile Duct Organoid Growth and Morphogenesis

Cholangiocyte organoids can be used to model liver biliary disease; however, both a defined matrix in which to emulate cholangiocyte self-assembly and the mechano-transduction pathways involved therein remain elusive. We designed a series of defined viscoelastic hyaluronan hydrogels in which to culture primary cholangiocytes and found that by mimicking the stress relaxation rate of liver tissue, we could induce cholangiocyte organoid growth and significantly increase expression of Yes-associated protein (YAP) target genes. Strikingly, inhibition of matrix metalloproteinases (MMPs) did not significantly affect organoid growth in 3D culture, suggesting that mechanical remodeling of the viscoelastic microenvironment - and not MMP-mediated degradation - is key to cholangiocyte organoid growth. By immobilizing jagged1 to the hyaluronan, stress relaxing hydrogel, self-assembled bile duct structures formed in organoid culture, indicating the synergistic effects of Notch signaling and viscoelasticity. By uncovering critical roles of hydrogel viscoelasticity, YAP signaling and Notch activation, we controlled cholangiocyte organogenesis, thereby paving the way for their use in disease modeling and/or transplantation.

bioengineering↗
bioRxiv2022

Human skeletal muscle ageing atlas

Skeletal muscle ageing increases the incidence of age-associated frailty and sarcopenia in the elderly worldwide, leading to increased morbidity and mortality. However, our understanding of the cellular and molecular mechanisms of muscle ageing is still far from complete. Here, we generate a single-cell and single-nucleus transcriptomic atlas of skeletal muscle ageing from 15 donors across the adult human lifespan, accompanied by myofiber typing using imaging. Our atlas reveals ageing mechanisms acting across different compartments of the muscle, including muscle stem cells (MuSCs), myofibers and the muscle microenvironment. Firstly, we uncover two mechanisms driving MuSC ageing, namely a decrease in ribosome biogenesis and an increase in inflammation. Secondly, we identify a set of nuclei populations explaining the preferential degeneration of the fast-twitch myofibers and suggest two mechanisms acting to compensate for their loss. Importantly, we identify a neuromuscular junction accessory population, which helps myofiber to compensate for aged-related denervation. Thirdly, we reveal multiple microenvironment cell types contributing to the inflammatory milieu of ageing muscle by producing cytokines and chemokines to attract immune cells. Finally, we provide a comparable mouse muscle ageing atlas and further investigate conserved and specific ageing hallmarks across species. In summary, we present a comprehensive human skeletal muscle ageing resource by combining different data modalities, which significantly expands our understanding of muscle biology and ageing.

genomics↗
bioRxiv2022

Robust and Versatile Arrayed Libraries for Human Genome-Wide CRISPR Activation, Deletion and Silencing

Arrayed CRISPR libraries extend the scope of gene-perturbation screens but require large numbers of efficacious sgRNA-expressing vectors. Using a newly invented liquid-phase plasmid cloning methodology, we constructed genome-wide arrayed libraries for human gene ablation (19,936 plasmids), activation, and epigenetic silencing (22,442 plasmids). At least 76% of each plasmid preparation encoded an intact array of 4 non-overlapping sgRNAs designed to tolerate most human DNA polymorphisms. We achieved perturbation efficacies of 75-99%, 76-92% and up to 10,000x in deletion, silencing and activation experiments, respectively. Upon conversion into massively parallel lentiviral vectors, an arrayed activation screen of 1,634 human transcription factors yielded 11 novel regulators of the cellular prion protein PrPC. Furthermore, a screen using a pooled version of the ablation library identified 5 novel modifiers of autophagy that went undetected with either of two 1sgRNA libraries. The CRISPR libraries described here represent a powerful resource for the targeted perturbation of human protein-coding genes.

genomics↗
bioRxiv2022

The evolutionary potential of the influenza A virus hemagglutinin is highly constrained by intersegment epistasis

The ongoing antigenic evolution of the influenza A virus (IAV) hemagglutinin (HA) gene limits efforts to effectively control the spread of the virus in the human population through vaccination. The factors that influence and constrain the evolutionary potential of the HA gene remain poorly understood. Efforts to understand the mechanisms that govern HA antigenic evolution typically examine the HA gene in isolation and ignore the importance of balancing HA receptor-binding activities with the receptor-destroying activities of the viral neuraminidase (NA) for maintaining viral fitness. We hypothesized that the need to maintain functional balance with NA significantly constrains the evolutionary potential of the HA gene. We used deep mutational scanning to show that variation in NA activity significantly reshapes the HA fitness landscape by modulating the overall mutational robustness of the HA protein. Consistent with this, we observe that different NA backgrounds support the emergence of distinct repertoires of HA escape variants under neutralizing antibody pressure. Our results reveal a critical role for intersegment epistatic interactions in shaping the evolutionary potential of the HA gene.

microbiology↗
bioRxiv2022

Comprehensive Analysis of the Expression and Prognosis for PSMBs in Clear Cell Renal Cell Carcinoma

BackgroundClear cell renal cell carcinoma (ccRCC) is one of the most common malignances with an ever-increasing incidence and high mortality. Although comprehensive therapy has made great progress in recent years, the prognosis of most ccRCC patients is still poor. The proteasome {beta} subunits (PSMBs) are a group of genes composing the ubiquitin-proteasome pathway, which is the principal mechanism of protein catabolism in mammalian cytoplasm and nucleus and is essential for the regulation of almost all cellular processes. Growing evidence show s that the PSMBs play an important role in the occurrence and progression of various cancers. However, the expression and prognostic value of PSMBs in ccRCC have not been evaluated. MethodsTo solve this issue, ONCOMINE, UALCAN, Human Protein Atlas, cBioPortal, Metascape, GeneMANIA, STRING, DAVID 6.8, TIMER were used in this study. ResultsThe transcriptional expression levels of PSMB2/4/7/8/9/10 in ccRCC tissues were found to be significantly upregulated, and the mRNA expression levels of PSMB1/2/3/4/8/9/10 were associated with advanced tumor stage and tumor grade. Besides, higher mRNA expression of PSMB1/2/3/4/5/6/7/10 were associated with a shorter overall survival (OS). Furthermore, the protein expression level of PSMB4/7/8/9/10 in ccRCC was higher than normal renal tissues. Significant relationships were also found between the expression of PSMBs and the infiltration of immune-related cells. ConclusionsThe present study implied that PSMB4 and PSMB10 might act as potential therapy targets and prognostic biomarkers in ccRCC, which may contribute to available knowledge, improve the treatment designs, and enhance the accuracy of prognosis for patients with ccRCC.

bioinformatics↗
bioRxiv2022

Analysis and Identification of Necroptosis Landscape on Therapy and Prognosis in Bladder Cancer

Bladder cancer (BLCA) is one of the most common malignant tumors of the urinary system, but current therapeutic strategy based on chemotherapy and immune checkpoint inhibitors (ICIs) therapy cannot meet the treatment needs, which mainly owing to the endogenous or acquired apoptotic resistance of cancer cells. Targeting necroptosis provides a novel strategy for chemotherapy, targeted drugs, and improves the efficacy of ICIs because of strong immunogenicity of necroptosis. Therefore, we systemically analyzed necroptosis landscape on therapy and prognosis in BLCA. We firstly divided BLCA patients from The Cancer Genome Atlas (TCGA) database into two necroptosis-related clusters (C1 and C2). Necroptosis C2 showed a significantly better prognosis than C1, and the differential genes of C2 and C1 were mainly related to the immune response according to GO and KEGG analysis. Next, we constructed a novel necroptosis related genes (NRGs) signature consisting of SIRT6, FASN, GNLY, FNDC4, SRC, ANXA1, AIM2, and IKBKB to predict the survival of TCGA-BLCA cohort, the accuracy of NRGsocre was also verified by external datasets. In addition, a nomogram combining NRGscore and several clinicopathological features was established to predict the BLCA patients OS more accurately and conveniently. We also found that NRGscore was significantly related to the infiltration levels of CD8 T cells, NK cells, and iDC cells, the gene expression of CTLA4, PD1, TIGIT, and LAG3 of TME, the sensitivity to chemotherapy and targeted agents in BLCA patients. In conclusion, the NRGscore has an excellent performance in evaluating the prognosis, clinicopathologic features, tumor microenvironment (TME) and therapeutic sensitivity of BLCA patients, which could be utilized as a guide for chemotherapy, ICIs therapy, and combination therapy.

cancer biology↗
bioRxiv2022

Multi-color live-cell STED nanoscopy of mitochondria with a gentle inner membrane stain

Capturing mitochondrias intricate and dynamic structure poses a daunting challenge for optical nanoscopy. Different labeling strategies have been demonstrated for live-cell stimulated emission depletion (STED) microscopy of mitochondria, but orthogonal strategies are yet to be established, and image acquisition has suffered either from photodamage to the organelles or from rapid photobleaching. Therefore, live-cell nanoscopy of mitochondria has been largely restricted to 2D single-color recordings of cancer cells. Here, by conjugation of cyclooctatetraene to a benzo-fused cyanine dye, we report a mitochondrial inner-membrane (IM) fluorescent marker, PK Mito Orange (PKMO), featuring efficient STED at 775 nm, strong photostability and markedly reduced phototoxicity. PKMO enables super-resolution recordings of inner-membrane dynamics for extended periods in immortalized mammalian cell lines, primary cells, and organoids. Photostability and reduced phototoxicity of PKMO open the door to live-cell 3D STED nanoscopy of mitochondria for three-dimensional analysis of the convoluted IM. PKMO is optically orthogonal with green and far-red markers allowing multiplexed recordings of mitochondria using commercial STED microscopes. Using multi-color STED, we demonstrate that imaging with PKMO can capture the sub-mitochondrial localization of proteins, or interactions of mitochondria with different cellular components, such as the ER or the cytoskeleton at sub-100 nm resolution. Thereby, this work offers a versatile tool for studying mitochondrial inner-membrane architecture and dynamics in a multiplexed manner.

cell biology↗
bioRxiv2022

Volitional generation of reproducible energy-efficient temporal patterns

One of the extraordinary characteristics of the biological brain is its low energy expense to implement a variety of biological functions and intelligence compared to the modern artificial intelligence (AI). Spike-based energy-efficient temporal codes have long been suggested as the contributor for the brain to run with a low energy expense. Despite this code having been largely reported in the sensory cortex, whether this code can be implemented in other brain areas to serve broader functions and how the brain learns to generate it have remained unaddressed. In this study, we designed a novel brain-machine interface (BMI) paradigm, by learning which two macaques could volitionally generate reproducible energy-efficient temporal patterns in the primary motor cortex (M1). Moreover, most neurons that were not directly assigned for controlling the BMI did not boost their excitability, demonstrating an overall energy-efficiency manner in performing the task. Over the course of learning, we found that the firing rates and temporal precision of selected neurons co-evolved to generate the energy-efficient temporal patterns, suggesting a cohesive rather than dissociable processing underlie the refinement of energy-efficient temporal patterns.

neuroscience↗
bioRxiv2022

Neural Implementation of Precise Temporal Patterns in Motor Cortex

One of the most concerned problems in neuroscience is how neurons communicate and convey information through spikes. There is abundant evidence in sensory systems to support the use of precise timing of spikes to encode information. However, it remains unknown whether precise temporal patterns could be generated to drive output in the primary motor cortex (M1), a brain area containing ample recurrent connections that may destroy temporal fidelity. Here, we used a novel brain-machine interface that mapped the temporal order and precision of motor cortex activity to the auditory cursor and reward to guide the generation of precise temporal patterns in M1. During the course of learning, rats performed the "temporal neuroprosthetics" in a goal-directed manner with increasing proficiency. Precisely timed spiking activity in M1 was volitionally and robustly produced under this "temporal neuroprosthetics", demonstrating the feasibility of M1 implementing temporal codes. Population analysis showed that the local network was coordinated in a fine time scale as the overall excitation heightened. Furthermore, we found that the directed connection between neurons assigned to directly control the output ("direct neurons") was strengthened throughout learning, as well as connections in the subnetwork that contains direct neurons. Network models revealed that excitatory gain and strengthening of subnetwork connectivity transitioned neural states to a more synchronous regime, which improved the sensitivity for coincidence detection and, thus, the precision of spike patterns. Therefore, our results suggested the recurrent connections facilitate the implementation of precise temporal patterns instead of impairing them, which provided new perspectives on the fine-timescale activity and dynamics of M1.

neuroscience↗
bioRxiv2022

A streamlined tandem tip-based workflow for sensitive nanoscale phosphoproteomics

Effective phosphoproteome of nanoscale sample analysis remains a daunting task, primarily due to significant sample loss associated with non-specific surface adsorption during enrichment of low stoichiometric phosphopeptide. We developed a novel tandem tip phosphoproteomics sample preparation method that is capable of sample cleanup and enrichment without additional sample transfer, and its integration with our recently developed SOP (Surfactant-assisted One-Pot sample preparation) and iBASIL (improved Boosting to Amplify Signal with Isobaric Labeling) approaches provides a streamlined workflow enabling sensitive, high-throughput nanoscale phosphoproteome measurements. This approach significantly reduces both sample loss and processing time, allowing the identification of >3,000 (>9,500) phosphopeptides from 1 (10) {micro}g of cell lysate using the label-free method without a spectral library. It also enabled precise quantification of [~]600 phosphopeptides from 100 cells sorted by FACS (single-cell level input for the enriched phosphopeptides) and [~]700 phosphopeptides from human spleen tissue voxels with a spatial resolution of 200 {micro}m (equivalent to [~]100 cells) in a high-throughput manner. The new workflow opens avenues for phosphoproteome profiling of mass-limited samples at the low nanogram level.

biochemistry↗
bioRxiv2022

In Silico Improvement of Highly Protective Anti-Malarial Antibodies

Antibody CIS43 binds Plasmodium falciparum circumsporozoite protein (PfCSP) and protects against malaria, as recently demonstrated clinically. To improve the efficacy of CIS43, we developed an in silico pipeline to optimize the interaction energy of CIS43 to its junctional epitope (peptide 21: PfCSP residues 101-115). Starting from two improved CIS43 variants, recently elicited from a CIS43-germline knock-in mice, single and double amino acid substitutions in the peptide 21-proximal heavy (VH) and light (VL) variable regions were introduced. CIS43-variants, selected on the basis of improved in silico interface and stability energies, showed increased affinity to peptide 21 and superior malaria-protective efficacy. The best designed variant, antibody P3-43, was significantly more protective than its template antibody m43.151, with greater liver-burden protection than the current best-in-class (antibody iGL-CIS43.D3). Crystal structures of improved antibodies revealed atomic-level interactions explaining gains in binding affinity. The reported pipeline provides a powerful in silico approach to improve antibody functionality.

immunology↗
bioRxiv2022

Drivers of nematode diversity in forest soils across climatic zones

Nematodes are the most abundant multi-cellular animals in soil, influencing key processes and functions in terrestrial ecosystems. Yet, little is known about the drivers of nematode abundance and diversity in forest soils across climatic zones. This is despite forests cover approximately 30% of the earths land surface, provide many crucial ecosystem services but strongly vary in hydrothermal conditions and associated ecosystem properties across climatic zones. Here, we collected nematode samples from 13 forests across a latitudinal gradient. We divided this gradient in temperate, warm-temperate, and tropical climatic zones. Using boosted regression trees, we showed that across the gradient, nematode abundance and diversity were mainly influenced by soil organic carbon. However, within climatic zones, other factors were more important in driving nematode alpha-diversity, nematode biomass and the abundance of different trophic groups: mean annual temperature and total soil phosphorus in temperate zones, soil pH in warm-temperate zones, and mean annual precipitation in tropical zones. Additionally, nematode beta-diversity was higher in temperate than in warm-temperate and tropical zones, and we did not find significant differences among climatic zones in nematode gamma diversity. Together, our findings indicate a latitudinal shift in the main climatic variables controlling soil nematode communities and demonstrate that the drivers of soil nematode diversity in forested ecosystems are affected by the spatial scale and climatic conditions considered. This implies that high resolution studies are needed to accurately predict how soil functions respond if climate conditions move beyond the coping range of soil organisms. Our results also emphasize the importance of studying the area-diversity relationship of soil organisms under different climatic conditions.

ecology↗
bioRxiv2022

Development of visual cortex in human neonates are selectively modified by postnatal experience

Experience-dependent cortical plasticity is a pivotal process of human brain development and essential for the formation of most cognitive functions. Although studies found that early visual experience could influence the endogenous development of visual cortex in animals, little is known about such impact on human infants. Using the multi-modal MRI data from developing human connectome project, we revealed the early structural and functional maps in the ventral visual cortex and their development across the first month of age. Particularly, we found the postnatal experience could modulate both the cortical morphology in ventral visual cortex and the functional circuit between bilateral primary visual cortices. But the cortical myelination and overall functional circuits of ventral cortex, particularly that of the high-order visual cortex, developed without significant influence of postnatal experience in such early period. These experience-dependent cortical properties were further validated in the preterm-born infants who have longer postnatal time but immature cortical development at birth. The results confirmed that the development of cortical thickness was dominated by the postnatal experience but the functional circuit might be determined by the overall maturity of visual cortex. These data suggest in human newborns that early postnatal experience shapes the structural and functional development of the visual cortex in selective and organized pattern.

neuroscience↗
bioRxiv2022

A Systematic Strategy for Identifying Causal Single Nucleotide Polymorphisms and Their Target Genes on Juvenile Arthritis Risk Haplotypes

IntroductionAlthough genome-wide association studies (GWAS) multiple regions conferring genetic risk for juvenile idiopathic arthritis (JIA), we are still faced with the task of identifying the single nucleotide polymorphisms (SNPs) on the disease haplotypes that exert the biological effects that confer risk. Until we identify the risk-driving variants, identifying the genes influenced by these variants, and therefore translating genetic information to improved clinical care, will remain an insurmountable task. We used a function-based approach for identifying causal variant candidates and the target genes on JIA risk haplotypes. MethodsWe used a massively parallel reporter assay (MPRA) in myeloid K562 cells to query the effects of 5,226 SNPs in non-coding regions on JIA risk haplotypes for their ability to alter gene expression when compared to the common allele. The assay relies on 180 bp oligonucleotide reporters ("oligos") in which the allele of interest is flanked by its cognate genomic sequence. Barcodes were added randomly by PCR to each oligo to achieve >20 barcodes per oligo to provide a quantitative read-out of gene expression for each allele. Assays were performed in both unstimulated K562 cells and cells stimulated overnight with interferon gamma (IFNg). As proof of concept, we then used CRISPRi to demonstrate the feasibility of identifying the genes regulated by enhancers harboring expression-altering SNPs. ResultsWe identified 553 expression-altering SNPs in unstimulated K562 cells and an additional 490 in cells stimulated with IFNg. We further filtered the SNPs to identify those plausibly situated within functional chromatin, using open chromatin and H3K27ac ChIPseq peaks in unstimulated cells and open chromatin plus H3K4me1 in stimulated cells. These procedures yielded 42 unique SNPs (total = 84) for each set. Using CRISPRi, we demonstrated that enhancers harboring MPRA-screened variants in the TRAF1 and LNPEP/ERAP2 loci regulated multiple genes, suggesting complex influences of disease-driving variants. ConclusionUsing MPRA and CRISPRi, JIA risk haplotypes can be queried to identify plausible candidates for disease-driving variants. Once these candidate variants are identified, target genes can be identified using CRISPRi informed by the 3D chromatin structures that encompass the risk haplotypes.

genetics↗