Biology subjects

Fan, G.

Publications and source records attributed to Fan, G..

At least 73 records · Page 4Linked to original sources

bioRxiv2021

Addressing Enzymatic-Independent Tumor-Promoting Function of NAMPT via PROTAC-Mediated Degradation

The rate-limiting enzyme of salvage pathway for NAD+ synthesis, NAMPT, is aberrantly overexpressed in a variety of tumor cells and is a poor prognosis factor for patient survival. NAMPT plays a major role in tumor cell proliferation, acting concurrently as an NAD+ synthase and unexpectedly, an extracellular ligand for several tumor-promoting signaling pathways. While previous efforts to modulate NAMPT activity were limited to enzymatic inhibitors with low success in clinical studies, protein degradation offers a possibility to simultaneously disrupt NAMPTs enzyme activity and ligand capabilities. Here, we report the development of two highly selective NAMPT-targeted proteolysis-targeting chimeras (PROTACs), which promoted rapid and potent NAMPT degradation in a cereblon-dependent manner in multiple tumor cell lines. Notably, both PROTAC degraders outperform a clinical candidate, FK866, in killing effect on hematological tumor cells. These results emphasize the importance and feasibility of applying PROTACs as a better strategy for targeting proteins like NAMPT with dual tumor-promoting functions, which are not easily achieved by conventional enzymatic inhibitors.

biochemistry↗

bioRxiv2021

Single-cell RNA Sequencing Reveals the Temporal Diversity and Dynamics of Cardiac Immunity after Myocardial Infarction

Myocardial infarction (MI) is strongly associated with the temporal regulation of cardiac immunity. However, a variety of current clinical trials have failed because of the lack of post-MI immunomodulating/anti-inflammatory targets. We performed single-cell RNA sequencing analysis of cardiac Cd45+ immune cell at 0, 3, 7, and 14 days after injury in a mouse left anterior descending coronary artery ligation model. Major immune cell populations, distinct subsets, and dynamic changes were identified. Macrophages (Mo)/monocytes were most abundant, peaking at 3 days after infarction. Mo-5 and Mo-6 were the predominant infiltrated subsets at this time point, with strong expression of inflammatory factors. Further analysis demonstrated that suppressing these sets attenuated pathological MI progression by preventing subsequent leukocyte extravasation and adverse remodeling. We also detected abundant apoptotic neutrophils and a profibrotic macrophage subset on days 7 and 14 respectively. These results provide a basis for developing cell type- and time-specific interventions in MI. Graphic abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=179 SRC="FIGDIR/small/452902v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@1d7c810org.highwire.dtl.DTLVardef@18f9c9dorg.highwire.dtl.DTLVardef@17325f7org.highwire.dtl.DTLVardef@c1a4e7_HPS_FORMAT_FIGEXP M_FIG C_FIG Temporal regulation of cardiac immunity is strongly associated with the onset, progression, and outcomes of MI. Our study of time-series scRNA-seq on the whole cardiac immune cells isolated from the LAD ligation mice and the tanshinone IIA treated mice shed light on the underlying pathology of MI.

cell biology↗

bioRxiv2021

Complexin-1 regulated transition in the assembly of single neuronal SNARE complex

Neurotransmitter release is mediated by the synaptic vesicle exocytosis. Important proteins in this process have been identified including the molecular machine Synaptic-soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) proteins, and other regulators. Complexin (Cpx) is one of the vital regulators in this process. The functions of Cpx are proposed to maintain a proper primed vesicle pool by preventing its premature depletion, which facilitates the vesicle fusion in the presence of Ca2+. However, the molecular mechanism remains unclear. Using dual-trap optical tweezers, we detected the interaction of complexin-1 (CpxI) with SNARE. We found that the CpxI stabilizes partially folded SNARE complexes by competing with C-terminal of Vamp protein and interacting with the C-terminal of t-SNARE complex.

biophysics↗

bioRxiv2021

Capacity to erase gene occlusion is a defining feature distinguishing naive from primed pluripotency

Pluripotent stem cells can exist in either the naive state representing a developmental blank slate or the downstream primed state poised for differentiation. Currently, known differences between these two states are mostly phenomenological, and none can adequately explain why the two states should differ in developmental priming. Gene occlusion is a mode of epigenetic inactivation that renders genes unresponsive to their cognate transcriptional activators. It plays a crucial role in lineage restriction. Here, we report that a defining feature distinguishing the two pluripotent states lies in the ability of naive but not primed cells to erase occlusion. This "deocclusion" capacity requires Esrrb, a gene expressed only in the naive but not primed state. Notably, Esrrb silencing in the primed state is itself due to occlusion. Collectively, our data argue that the Esrrb-dependent deocclusion capacity in naive cells is key for sustaining naive pluripotency, and the loss of this capacity in the primed state via the occlusion of Esrrb poises cells for differentiation.

molecular biology↗

bioRxiv2021

Catching a liar through facial expression of fear

The leakage theory in the field of deception detection predicted that liars could not repress the leaked felt emotions (e.g., the fear or delight); and people who were lying would feel fear (to be discovered), especially under the high-stake situations. Therefore, we assumed that the aim of revealing deceits could be reached via analyzing the facial expression of fear. Detecting and analyzing the subtle leaked fear facial expressions is a challenging task for laypeople. It is, however, a relatively easy job for computer vision and machine learning. To test the hypothesis, we analyzed video clips from a game show "The moment of truth" by using OpenFace (for outputting the Action Units of fear and face landmarks) and WEKA (for classifying the video clips in which the players was lying or telling the truth). The results showed that some algorithms could achieve an accuracy of greater than 80% merely using AUs of fear. Besides, the total durations of AU 20 of fear were found to be shorter under the lying condition than under the truth-telling condition. Further analysis found the cause why durations of fear were shorter was that the duration from peak to offset of AU20 under the lying condition was less than that under the truth-telling condition. The results also showed that the facial movements around the eyes were more asymmetrical while people telling lies. All the results suggested that there do exist facial clues to deception, and fear could be a cue for distinguishing liars from truth-tellers.

neuroscience↗

bioRxiv2020

Sequencing of clinical samples reveals that adaptation keeps establishing during H7N9 virus infection in humans

The H7 subtype avian influenza viruses (AIV) have a much longer history and their adaptation through evolution pose continuous threat to humans 1. Since 2013 March, the novel reasserted H7N9 subtype have transmitted to humans through their repeated assertion in the poultry market. Through repeated transmission, H7N9 gradually became the second AIV subtype posing greater public health risk after H5N1 2,3. After infection, how the virus tunes its genome to adapt and evolve in humans remains unknown. Through direct amplification of H7N9 and high throughput (HT) sequencing of full genomes from the swabs and lower respiratory tract samples collected from infected patients in Shenzhen, China, we have analyzed the in vivo H7N9 mutations at the level of whole genomes and have compared with the genomes derived by in vitro cultures. These comparisons and frequency analysis against the H7N9 genomes in the public database, 40 amino acids were identified that play potential roles in virus adaptation during H7N9 infection in humans. Various synonymous mutations were also identified that might be crucial to H7N9 adaptation in humans. The mechanism of these mutations occurred in a single infection are discussed in this study.

microbiology↗

bioRxiv2020

Symbiont-Screener: a reference-free filter to automatically separate host sequences and contaminants for long reads or co-barcoded reads by unsupervised clustering

Decontamination is necessary for eliminating the effect of foreign genomes on the symbiont studies and biomedical discoveries. However, direct extraction of host sequencing reads with no references remains challenging. Here, we present a triobased method to classify the host error-prone long reads or sparse co-barcoded reads prior to assembly, free of any alignments against DNA or protein references. This method first identifies high-confident host reads by haplotype-specific k-mers inherited from parents, and then groups remaining host reads by the unsupervised clustering. Experimental results demonstrated that this approach successfully classified up to 97.38% of the host human long reads with the precision rate of 99.9999%, and 79.95% host co-barcoded reads with the precision rate of 98.36% using an artificially mixed data. Moreover, the tool also exhibited a good performance on the decontamination of the real algae data. The purified reads reconstructed two haplotypes and improved the assembly with larger contig NGA50 value and less misassemblies. Symbiont-Screener can be freely downloaded at https://github.com/BGI-Qingdao/Symbiont-Screener.

bioinformatics↗

bioRxiv2020

Robust Benchmark Structural Variant Calls of An Asian Using the State-of-Art Long Fragment Sequencing Technologies

The importance of structural variants (SVs) on phenotypes and human diseases is now recognized. Although a variety of SV detection platforms and strategies that vary in sensitivity and specificity have been developed, few benchmarking procedures are available to confidently assess their performances in biological and clinical research. To facilitate the validation and application of those approaches, our work established an Asian reference material comprising identified benchmark regions and high-confidence SV calls. We established a high-confidence SV callset with 8,938 SVs in an EBV immortalized B lymphocyte line, by integrating four alignment-based SV callers [from 109x PacBio continuous long read (CLR), 22x PacBio circular consensus sequencing (CCS) reads, 104x Oxford Nanopore long reads, and 114x optical mapping platform (Bionano)] and one de novo assembly-based SV caller using CCS reads. A total of 544 randomly selected SVs were validated by PCR and Sanger sequencing, proofing the robustness of our SV calls. Combining trio-binning based haplotype assemblies, we established an SV benchmark for identification of false negatives and false positives by constructing the continuous high confident regions (CHCRs), which cover 1.46Gb and 6,882 SVs supported by at least one diploid haplotype assembly. Establishing high-confidence SV calls for a benchmark sample that has been characterized by multiple technologies provides a valuable resource for investigating SVs in human biology, disease, and clinical diagnosis.

genomics↗

bioRxiv2020

FER-mediated tyrosine phosphorylation and PIK3R2/p85β recruitment on IRS4 promotes the PI3K-AKT signaling pathway and tumorigenesis in ovarian cancer

Tyrosine phosphorylation, orchestrated by tyrosine kinases and phosphatases, modulates a multi-layered signaling network in a time and space dependent manner. Dysregulation of this post-translational modification is inevitably associated with pathological diseases. Our previous work has demonstrated that non-receptor tyrosine kinase FER is upregulated in ovarian cancer. Knockdown of the kinase attenuates metastatic phenotypes in tumor cells. Here we employed mass spectrometry and biochemical approaches to identify IRS4 as a novel substrate of FER. Using a proximity-based tagging system, we determined that FER-mediated phosphorylation of Tyr779 enables IRS4 to recruit PIK3R2/p85{beta}, the regulatory subunit of PI-3K, and activate the PI3K-AKT pathway. Rescuing IRS4-null ovarian tumor cells with phosphorylation-defective mutant, but not WT IRS4, delayed tumor cell proliferation both in vitro and in vivo. Overall, we revealed a kinase-substrate regulatory mode between FER and IRS4, and the pharmacological inhibition of FER kinase may be beneficial for ovarian cancer patients with PI3K-AKT hyperactivation.

molecular biology↗

bioRxiv2020

Comparative analysis of clonal evolution among patients with right-sided colon cancer, left-sided colon cancer and rectal cancer

Background Tumor multi-region sequencing reveals intratumor heterogeneity (ITH) and clonal evolution which play a key role in progression and metastases of the tumor. However, large-scale high depths multiregional sequencing of colorectal cancer (CRC) has not been well studied. In addition, the comparative analysis among right-sided colon cancer (RCC), left-sided colon cancer (LCC) and rectal cancer (RC) patients as well as the study of lymph node metastasis (LN) with extranodal tumor deposits (ENTD) from evolutionary perspective remain unknown.Results In this prospective study, we recruited different stages of 68 CRC patients with RCC (18), LCC (20) and RC (30). We performed high-depth whole exome sequencing (WES) of 206 tumor regions including 176 primary tumors, 19 LN and 11 ENTD samples. Our results showed ITH with a Darwinian pattern of evolution. We identified that the evolution pattern of LCC and RC was more complex and divergent than RCC, suggesting the evolutionary diversity in the initiation and progression of LCC and RC. Genetic and evolutionary evidences found that both LN and ENTD were of polyclonal in origin. Moreover, ENTD was a distinct entity from LN and evolved later.Conclusions In conclusion, our study showed the Darwinian pattern of evolution with differences in clonal evolution between RCC with LCC and RC.Competing Interest StatementThe authors have declared no competing interest.View Full Text

cancer biology↗

bioRxiv2020

In situ structure of the AcrAB-TolC efflux pump at subnanometer resolution

In Gram-negative bacteria, tripartite efflux pump AcrAB-TolC plays a prominent role in antibiotic resistance. We have used high resolution cryo-ET to visualize the structure of Escherichia coli AcrAB-TolC at a 7 [A] resolution in intact cells. The resulting structures show the detailed architecture of the assembled complex embedded into cell envelope. Interactions with the inner membrane enable crosstalk between AcrB and TolC through AcrA, suggesting that assembly in the native cellular environment is critical for the pump activation mechanism, where the allosteric activating signal is triggered by the alternate binding of AcrA to the lipid membrane and AcrB porter domain. We establish a platform for high resolution in situ structural studies of bacteria efflux pump, which can yield critical information in understanding complex assemblies function. One sentence summaryA 7 [A] in situ structure of the AcrAB-TolC pump from bacteria by cryo-ET reveals mechanisms for active efflux.

biophysics↗

bioRxiv2020

Haplotype-Resolved Assembly for Synthetic Long Reads Using a Trio-Binning Strategy

The accuracy and completeness of genome haplotyping are crucial for characterizing the relationship between human disease susceptibility and genetic variations, especially for the heterozygous variations. However, most of current variations are unphased genotypes, and the construction of long-range haplotypes remains challenging. We introduced a de novo haplotype-resolved assembly tool, HAST that exports two haplotypes of a diploid species for synthetic long reads with trio binning. It generates parental distinguishing k-mer libraries, partitions reads from the offspring according to the unique markers, and individually assembles them to resolve the haplotyping problem. Based on the stLFR co-barcoding data of an Asian as well as his parental massive parallel sequencing data, we utilized HAST to recover both haplotypes with a scaffold N50 of >11 Mb and an assembly accuracy of 99.99995% (Q63). The complete and accurate employment of long-range haplotyping information provided sub-chromosome level phase blocks (N50 [~]13 Mb) with 99.6% precision and 94.1% recall on average. We suggest that the accurate and efficient approach accomplishes the regeneration of the haplotype chromosomes with trio binning, thus promoting the determination of haplotype phase, the heterosis of crossbreeding, and the formation of autopolyploid and allopolyploid.

bioinformatics↗

bioRxiv2020

Chromosome-level genome assembly of the African pike, Hepsetus odoe

The order Characiformes is one of the largest components of the freshwater teleost fauna inhabiting exclusively in South America and Africa with great ecological and economical significance. Yet, quite limited genomic resources are available to study this group and their transatlantic vicariance. In this study we present a chromosome-level genome assembly of the African pike (Hepsetus odoe), a representative member of the African Characiformes. To this end, we generated 119, 11, and 67 Gb reads using the single tube long fragment read (stLFR), Oxford Nanopore, and Hi-C sequencing technologies, respectively. We obtained an 862.1 Mb genome assembly with the contig and scaffold N50 of 347.4 kb and 25.8 Mb, respectively. Hi-C sequencing produced 29 chromosomes with 742.5 Mb, representing 86.1% of the genome. 24,314 protein-coding genes were predicted and 23,999 (98.7%) genes were functionally annotated. The chromosomal-scale genome assembly will be useful for functional and evolutionary studies of the African pike and promote the study of Characiformes speciation and evolution.

genomics↗

bioRxiv2020

De novo synthesis and salvage pathway coordinately regulates polyamine homeostasis and determines T cell proliferation and function.

Robust and effective T cell-mediated immune responses require proper allocation of metabolic resources through metabolic pathways to sustain the energetically costly immune response. As an essential class of polycationic metabolites ubiquitously present in all living organisms, the polyamine pool is tightly regulated by biosynthesis and salvage pathway. We demonstrated that arginine is a major carbon donor and glutamine is a minor carbon donor for polyamine biosynthesis in T cells. Accordingly, the dependence of T cells can be partially relieved by replenishing the polyamine pool. In response to the blockage of de novo synthesis, T cells can rapidly restore the polyamine pool through a compensatory increase in polyamine uptake from the environment, indicating a layer of metabolic plasticity. Simultaneously blocking synthesis and uptake depletes the intracellular PA pool, inhibits T cell proliferation, suppresses T cell inflammation, indicating the potential therapeutic value of targeting the polyamine for managing inflammatory and autoimmune diseases.

cell biology↗

bioRxiv2020

Potentiating the anti-tumor response of tumor infiltrated T cells by NAD+ supplementation

Tumor immunotherapies have provided clinical benefits, yet great potential remains for optimizing therapeutic effects. Here, we show that low NAD+ levels restrict the function of tumor infiltrating T lymphocytes (TILs). TILs harvested from human ovarian tumor tissues showed decreased NAD+ levels compared with T cells from paired peripheral blood samples. The combination of whole-genome CRISPR and large-scale metabolic inhibitor screens implicated the NAD+ biosynthesis enzyme nicotinamide phosphoribosyltransferase (NAMPT) is required for T cell activation. Further isotopic labeling and LC-MS studies confirmed that NAD+ depletion suppressed mitochondrial energy biosynthesis in T cells. Excitingly, NAD+ supplementation significantly enhanced the tumor cell-killing efficacy of CAR-T cells ex vivo, and extended animal survive in both adoptive CAR-T model and immune checkpoint blockade treatment models in vivo. This study demonstrates an over-the-counter nutrient supplement NAD+ could robustly boost the efficacy of T cell-based immunotherapy and provides insights into the cellular basis of T cell metabolic reprogramming in treating cancers. One Sentence SummaryNAD+ supplementation during cancer immunotherapies significantly enhances T cell activation and tumor killing capacity.

immunology↗

bioRxiv2020

X-chromosome dosage compensation dynamics in human early embryos

In mammals, female cells are obliged to inactivate one of two X chromosomes to achieve dosage parity with the single X chromosome in male cells, and it is also thought that the single active X chromosome is increased 2-fold to achieve dosage balance with two sets of autosomes (X:A ratio = 1, or Ohnos hypothesis). However, the ontogeny of X-chromosome inactivation and augmentation of the single active X remains unclear during human embryogenesis. Here, we perform single-cell RNA-seq analysis to examine the timing of X:A balancing and X-inactivation (XCI) in pre- and peri-implantation human embryos up to fourteen days in culture. We find that X-chromosome gene expression in both male and female preimplantation embryos is approximately balanced with autosomes (X:A ratio = 1) after embryonic genome activation (EGA) and persists through fourteen days in vitro. Cross-species analysis of preimplantation embryo also show balanced X:A ratio within the first few days of development. By single-cell mRNA SNP profiling, we find XCI beginning in day 6-7 blastocyst embryos, but does not affect X:A dosage balance. XCI is most evident in trophoectoderm (TE) cells, but can also be observed in a small number of inner cell mass (ICM)-derived cells including primitive endoderm (PE) and epiblast (EPI) cells. Analysis between individual XaXa and XaXi sister cells from the same embryo reveals random XCI and persistently balanced X:A ratio, including sister cells transitioning between XaXa and XaXi states. We therefore conclude that the male X-chromosome undergoes X chromosome augmentation prior to the simultaneous X-chromosome inactivation and augmentation in females. Together, our data demonstrate an evolutionally conserved model of X chromosome dosage compensation in humans and other mammalian species.

developmental biology↗

bioRxiv2020

Genomic analyses reveal the origin of domestic ducks and identify different genetic underpinnings of wild ducks

Domestic ducks are considered to have been tamed from the mallard or a descendant of the mallard and the spot-billed duck. Domestic ducks show remarkable phenotypic variation in morphology, physiology and behaviour. However, the molecular genetics of the origin and phenotypic variation of ducks are still poorly studied. Here, we present mallard and spot-billed genomes and perform whole-genome sequencing on eight domestic duck breeds and eight wild duck species. Surprisingly, analyses of these data support a model in which domestic ducks diverged from their closest wild lineage (mallard ducks and spot-billed ducks) at the last glacial period (LGP, 100-300 kilo years ago (Kyr)). The wild lineage further speciated into mallard ducks and spot-billed ducks approximately 70 Kyr, whereas the domestic lineage population decreased through the LGP. A scan of wild duck genomes compared with domestic duck genomes identified numerous loci that may have been affected by positive selection in ancestral wild ducks after their divergence from domestic lineages. Function analyses suggested that genes usually affecting organ development and energy metabolism may involve long-distance flight ability. Further selective sweep analyses identified two genes associated with egg production and three genes related to feeding modulation under selection in domestic ducks. These analyses unravel a distinct evolutionary pattern of ducks and two wild duck de novo genomes, thus providing a novel resource for speciation studies.

genomics↗

bioRxiv2020

Three genomes of Osteoglossidae shed light on ancient teleost evolution

Osteoglossiformes is a basal clade of teleost, originated from late Jurassic and had seen the process of continental drift. The genomic differences amongst Osteoglossiformes species should reflect the unique evolve history of that time. Here, we presented the chromosome-level genome of Heterotis niloticus which is the only omnivore species of Osteoglossidae spreading in Africa. Together with other two Osteoglossidae species genomes of Arapaima gigas and Scleropages formosus which spread in South America and Australia respectively, we found great evolutionary differences in gene families and transposable elements. Phylogenetic analysis showed that the ancestor of H. niloticus and A. gigas diverged with S. formosus at [~]106.1Mya, consistent with the time of Afro-South American drift and A. gigas speciated from the ancestor of H. niloticus and A. gigas at [~]59.2 Mya, consistent with the separation of Eurasia and North American continents. And we proposed the evolutionary traces of Osteoglossidae species based on comparative genomics analysis and their living geographic habitats. We identified loss of LINEs and LTRs, fast evolutionary rate in parallel to fast pseudogenization rate in H. niloticus and A. gigas comparing to S. formosus during the evolutionary process. We also found notable OR genes contraction in H. niloticus, which might be related to the diet transition. Taken together, we reconstructed the evolutionary process of Osteoglossidae using three representative genomes, providing a possible clue for biogeographic and evolution study of ancient teleost clade.

genomics↗