Biology subjects

Su, W.

Publications and source records attributed to Su, W..

48 records · Page 3Linked to original sources

bioRxiv2021

Experimental and mathematical insights on the interactions between poliovirus and a defective interfering genome

1During replication, RNA viruses accumulate genome alterations, such as mutations and deletions. The interactions between individual variants can determine the fitness of the virus population and, thus, the outcome of infection. To investigate the effects of defective interfering genomes (DI) on wild-type (WT) poliovirus replication, we developed an ordinary differential equation model. We experimentally determined virus and DI replication during co-infection, and use these data to infer model parameters. Our model predicts, and our experimental measurements confirm, that DI replication and encapsidation are the most important determinants for the outcome of the competition. WT replication inversely correlates with DI replication. Our model predicts that genome replication and effective DI genome encapsidation are critical to effectively inhibit WT production, but an equilibrium can be established which enables WT to replicate, albeit to reduce levels.

microbiology↗

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

The genomic and transcriptomic foundations of viviparous seed development in mangroves

Vivipary in plants refers to a specific seed development and reproductive strategy where seeds minimize the dormancy stage and germinate while still attached to their maternal plants. It is one of the most unique adaptive genetic features used by many mangrove species where elongated hypocotyls aid in quick root emergence to anchor the seedling in coastal intertidal wetlands. The genetic mechanisms behind mangrove vivipary, however, remain elusive. Using comparative genomic and transcriptomic technologies to investigate viviparous mangroves and their close inland relatives, we found that a full array of gene expression profiles were altered, including key plant hormone metabolic pathways, high expression of embryonic signature genes, and reduced production of proanthocyanidins and storage proteins. Along with these changes, a major gene regulating seed dormancy, Delay of Germination-1 (DOG1), is entirely missing or defunct within the entire linage of the four genera with true viviparous characteristics. These results suggest a systemic level change is required to warrant the genetic program of mangrove vivipary. Understanding of the molecular processes of vivipary could benefit the design of pregerminated propagules for forestation in harsh environments or prevent precocious germination of grain crops pre- and post-harvest.

genomics↗

bioRxiv2020

Ectopic expression of a maize gene is induced by Composite Insertions generated by Alternative Transposition

Transposable elements (TEs) are DNA sequences that can mobilize and proliferate throughout eukaryotic genomes. Previous studies have shown that in plant genomes, TEs can influence gene expression in various ways such as inserting in introns or exons to alter transcript structure and content, and providing novel promoters and regulatory elements to generate new regulatory patterns. Furthermore, TEs can also regulate gene expression at the epigenetic level by modifying chromatin structure, changing DNA methylation status and generating small RNAs. In this study, we demonstrated that Ac/fAc transposable elements are able to induce ectopic gene expression by duplicating and shuffling enhancer elements. Ac/fAc elements belong to the hAT family of Class II TEs. They can undergo standard transposition events, which involve the two termini of a single transposon, or alternative transposition events which involve the termini of two different, nearby elements. Our previous studies have shown that alternative transposition can generate various genome rearrangements such as deletions, duplications, inversions, translocations and Composite Insertions (CIs). We identified over 50 independent cases of CIs generated by Ac/fAc alternative transposition and analyzed 10 of them in detail. We show that these CIs induced ectopic expression of the maize pericarp color 2 (p2) gene, which encodes a Myb-related protein. All the CIs analyzed contain sequences including a transcriptional enhancer derived from the nearby p1 gene, suggesting that the CI-induced activation of p2 is effected by mobilization of the p1 enhancer. This is further supported by analysis of a mutant in which the CI is excised and p2 expression is lost. These results show that alternative transposition events are not only able to induce genome rearrangements, but also generate Composite Insertions that can control gene expression. SummaryWhen Barbara McClintock originally identified and characterized Transposable Elements (TEs) in maize, she termed them "Controlling Elements" due to their effects on gene expression. Here we show that maize Ac/Ds TEs can acquire a genomic enhancer and generate Composite Insertions (CIs) that activate expression of a nearby gene. CIs are structurally variable elements that include TE termini enclosing sequences from an original donor locus, and are formed when the termini of two nearby TEs transpose during S phase from a replicated to unreplicated site. In this way, TEs may acquire genomic enhancers to generate Controlling Elements as described by McClintock.

genetics↗

bioRxiv2020

De novo design of ACE2 protein decoys to neutralize SARS-CoV-2

There is an urgent need for the ability to rapidly develop effective countermeasures for emerging biological threats, such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes the ongoing coronavirus disease 2019 (COVID-19) pandemic. We have developed a generalized computational design strategy to rapidly engineer de novo proteins that precisely recapitulate the protein surface targeted by biological agents, like viruses, to gain entry into cells. The designed proteins act as decoys that block cellular entry and aim to be resilient to viral mutational escape. Using our novel platform, in less than ten weeks, we engineered, validated, and optimized de novo protein decoys of human angiotensin-converting enzyme 2 (hACE2), the membrane-associated protein that SARS-CoV-2 exploits to infect cells. Our optimized designs are hyperstable de novo proteins ([~]18-37 kDa), have high affinity for the SARS-CoV-2 receptor binding domain (RBD) and can potently inhibit the virus infection and replication in vitro. Future refinements to our strategy can enable the rapid development of other therapeutic de novo protein decoys, not limited to neutralizing viruses, but to combat any agent that explicitly interacts with cell surface proteins to cause disease.

biochemistry↗

bioRxiv2020

Active Time-Restricted Feeding Protects the Blood Pressure Circadian Rhythm in Diabetic Mice

The quantity and quality of food intake have been considered crucial for peoples wellness. Only recently has it become appreciated that the timing of food intake, independent of total calorie consumption, is also critical. The involvement and contribution of the timing of food intake in nondipping blood pressure (BP), the most common disruption of the BP circadian rhythm in diabetes, however, remains uncertain. Here, we demonstrate that the loss of diurnal rhythm in food intake coincided with nondipping BP in type 2 diabetic db/db mice, and imposing a food intake diurnal rhythm by active time-restricted feeding (ATRF) remarkably prevented db/db mice from the development of nondipping BP. Moreover, ATRF, independent of calorie restriction, also effectively restored the already disrupted BP circadian rhythm in db/db mice. Mechanistically, ATRF reduced the sympathetic vascular tone and BP during the light phase via fasting, thus protecting the BP circadian rhythm in db/db mice. Moreover, we identified BMAL1, an obligatory core clock gene, as a potentially key molecule that links ATRF, sympathetic vascular tone, and BP circadian rhythm. Collectively, these data reveal an important but previously unrecognized role of the timing of food intake in the onset, prevention, and treatment of nondipping BP in diabetes.

physiology↗

bioRxiv2020

Construction of High Content Nanobody Library in Mammalian Cells by Linear-double-stranded DNA Based Strategies

Here, we developed two novel methods to construct high content nanobody library in mammalian cells. For the first method, we employed a linear-double-stranded DNA based AND-gate (LBAG) strategy. Upstream- and downstream-linear-double-stranded DNAs (ldsDNAs), containing identical overlapping sequences, were co-transfected into cultured cell lines to conduct AND-gate calculation to form intact nanobody expression cassette. For the second method, we generated full-length nanobody expression ldsDNA by in vitro ligation of restrict cut up- and down-stream ldsDNAs. Then the ldsDNAs were directly transfected into mammalian cells to express nanobody library. Both methods generated over a million different nanobody sequences as revealed by high-throughput sequencing (HTS).

immunology↗

bioRxiv2020

Compartmentalization of enhanced biomolecular interactions for high-throughput drug screening in test tubes

Modification-dependent and -independent biomolecular interactions (BIs), including protein-protein, protein-DNA/RNA and protein-lipid, play crucial roles in all cellular processes. Dysregulation of BIs or malfunction of the associated enzymes results in various diseases, thus they are attractive targets for therapies. High-throughput screening (HTS) can greatly facilitate the discovery of drugs for these targets. Here we describe a HTS drug discovery method, called compartmentalization of enhanced biomolecular interactions in test tubes (CEBIT). CEBIT uses selective recruitment of biomolecules into phase separated compartments harboring their cognate binding partners as readouts. CEBIT were tailored to detect various BIs and associated modifying enzymes. Using CEBIT-based HTS assays, we successfully identified known inhibitors of the p53/MDM2 interaction and of SUV39H1 from a compound library. CEBIT is simple and versatile, and is likely to become a powerful tool for drug discovery and basic biomedical research.

biophysics↗

bioRxiv2019

Influenza H3 and H1 hemagglutinins have different genetic barriers for resistance to broadly neutralizing stem antibodies

In the past decade, the discovery and characterization of broadly neutralizing antibodies (bnAbs) to the highly conserved stem region of influenza hemagglutinin (HA) have provided valuable insights for development of a universal influenza vaccine. However, the genetic barrier for resistance to stem bnAbs has not been thoroughly evaluated. Here, we performed a series of deep mutational scanning experiments to probe for resistance mutations. We found that the genetic barrier to resistance to stem bnAbs is generally very low for the H3 subtype but substantially higher for the H1 subtype. Several resistance mutations in H3 cannot be neutralized by stem bnAbs at the highest concentration tested, do not reduce in vitro viral fitness and in vivo pathogenicity, and are often present in circulating strains as minor variants. Thus, H3 HAs have a higher propensity than H1 HAs to escape major stem bnAbs and creates a potential challenge in the development of a bona fide universal influenza vaccine. ONE SENTENCE SUMMARYAcquisition of resistance by influenza virus to broadly neutralizing hemagglutinin stem antibodies varies tremendously depending on subtype.

microbiology↗

bioRxiv2019

Benchmarking Transposable Element Annotation Methods for Creation of a Streamlined, Comprehensive Pipeline

Sequencing technology and assembly algorithms have matured to the point that high-quality de novo assembly is possible for large, repetitive genomes. Current assemblies traverse transposable elements (TEs) and allow for annotation of TEs. There are numerous methods for each class of elements with unknown relative performance metrics. We benchmarked existing programs based on a curated library of rice TEs. Using the most robust programs, we created a comprehensive pipeline called Extensive de-novo TE Annotator (EDTA) that produces a condensed TE library for annotations of structurally intact and fragmented elements. EDTA is open-source and freely available: https://github.com/oushujun/EDTA.

genomics↗

bioRxiv2018

Generation of Highly Diverse Peptide Library by Linear-double-stranded DNA Based AND Logic Computation in Mammalian Cells

DNA-encoded peptide libraries are ideal functional peptide discovery platforms for their extremely large capacity. However, its still difficult to build high content peptide library in intact mammalian cells, which offer advantages associated with appropriate protein modification, proper protein folding, and natural status of membrane protein. Our previous work established linear-double-stranded DNAs (ldsDNAs) as innovative biological parts to implement AND gate genetic circuits in mammalian cell line. In the current study, we employ ldsDNA with terminal NNK degenerate codons as AND gate input to build highly diverse peptide library in mammalian cells. This ldsDNA-based AND gate (LBAG) peptide strategy is easy to conduct, only PCR reaction and cell transfection experiments are needed. High-throughput sequencing (HTS) results reveal that our new LBAG strategy could generate peptide library with both amino acid sequence and peptide length diversities. Moreover, by a mammalian cell two-hybrid system, we pan an MDM2 protein interacting peptide through the LBAG peptide library. Our work establishes ldsDNA as biological parts for building highly diverse peptide library in mammalian cells.

bioengineering↗

bioRxiv2018

Linear-double-stranded DNA (ldsDNA) based AND logic computation in mammalian cells

Synthetic biology employs engineering principles to redesign biological system for clinical or industrial purposes. The development and application of novel genetic devices for genetic circuits construction will facilitate the rapid development of synthetic biology. Here we demonstrate that mammalian cells could perform two- and three-input linear-double-stranded DNA (ldsDNA) based Boolean AND logic computation. Through hydrodynamic ldsDNA delivery, two-input ldsDNA-base AND-gate computation could be achieved in vivo. Inhibition of DNA-PKcs expression, a key enzyme in non-homologous end joining (NHEJ), could significantly downregulate the intensity of output signals from ldsDNA-based AND-gate. We further reveal that in mammalian cells ldsDNAs could undergo end processing and then perform AND-gate calculation to generate in-frame output proteins. Moreover, we show that ldsDNAs or plasmids with identical overlapping sequences could also serve as inputs of AND-gate computation. Our work establishes novel genetic devices and principles for genetic circuits construction, thus may open a new gate for the development of new disease targeting strategies and new protein genesis methodologies.

synthetic biology↗