Biology subjects

Ding, Y.

Publications and source records attributed to Ding, Y..

At least 271 records · Page 15Linked to original sources

bioRxiv2019

Extensive Mammalian Germline Genome Engineering

Xenotransplantation, specifically the use of porcine organs for human transplantation, has long been sought after as an alternative for patients suffering from organ failure. However, clinical application of this approach has been impeded by two main hurdles: 1) risk of transmission of porcine endogenous retroviruses (PERVs) and 2) molecular incompatibilities between donor pigs and humans which culminate in rejection of the graft. We previously demonstrated that all 25 copies of the PERV elements in the pig genome could be inactivated and live pigs successfully generated. In this study, we improved the scale of porcine germline editing from targeting a single repetitive locus with CRISPR to engineering 13 different genes using multiple genome engineering methods. we engineered the pig genome at 42 alleles using CRISPR-Cas9 and transposon and produced PERVKO{middle dot}3KO{middle dot}9TG pigs which carry PERV inactivation, xeno-antigen KO and 9 effective human transgenes. The engineered pigs exhibit normal physiology, fertility, and germline transmission of the edited alleles. In vitro assays demonstrated that these pigs gain significant resistance to human humoral and cell mediated damage, and coagulation dysregulations, similar to that of allotransplantation. Successful creation of PERVKO{middle dot}3KO{middle dot}9TG pigs represents a significant step forward towards safe and effective porcine xenotransplantation, which also represents a synthetic biology accomplishment of engineering novel functions in a living organism. One Sentence SummaryExtensive genome engineering is applied to modify pigs for safe and immune compatible organs for human transplantation

synthetic biology↗

bioRxiv2019

Digital polymerase chain reaction in an array of microfluidic printed droplets

Digital polymerase chain reaction (PCR) is a fast-developed technology, which makes it possible to provide absolute quantitative results. However, this technology has not been widely used in research field or clinical diagnostics. Although digital PCR has been born for two decades, the products on this subject still suffer from either high cost or cumbersome user experience, hence very few labs have the willingness or budget to routinely use such product; On the other hand, the unique sensitivity of dPCR over traditional qPCR shows great potential applications. Here, a cost-effective digital PCR method based on a microfluidic printing system was introduced, trying to overcome those shortcomings. The microfluidic droplet printing technology was utilized in this study to directly generate droplet array containing PCR reaction solution onto the simple glass substrate for the subsequent PCR and imaging, which could be done with any regular flat-panel PCR machine and microscope. The method introduces a new perspective in droplet-based digital PCR in that the droplets generated with this method aligns well in an array without touch with each other, therefore the regular glass and oil could be used without any special surfactant. With simple analysis, the data generated with this method showed reliable quality, which followed the Poisson distribution trend. Compared with other expensive digital PCR methods, this system is more affordable and simpler to integrate, especially for those biological or medical labs which are in need for the digital PCR options but short in budget. Therefore, this method is believed to have the great potential in the future market application.

molecular biology↗

bioRxiv2019

microRNA seedless sites attenuate strong-seed-site-mediated target repression

MicroRNAs (miRNAs) regulate protein-coding gene expression primarily through cognitive binding sites in the 3 untranslated regions (3' UTRs). Seed sites are sequences in messenger RNAs (mRNAs) that form perfect Watson-Crick base-paring with a miRNAs seed region, which can effectively reduce mRNA abundance and/or repress protein translation. Some seedless sites, which do no form perfect seed-pairing with a miRNA, can also lead to target repression, often with lower efficacy. Here we report the surprising finding that when seedless sites and seed sites are co-present in the same 3UTR, seedless sites attenuate strong-seed-site-mediated target suppression, independent of 3' UTR length. This attenuation effect is detectable in >70% of transcriptomic datasets examined, in which specific miRNAs are experimentally increased or decreased. The attenuation effect is confirmed by 3UTR reporter assays and mediated through base-pairing between miRNA and seedless sites. Furthermore, this seedless-site-based attenuation effect could affect seed sites of the same miRNA or another miRNA, thus partially explaining the variability in target suppression and miRNA-mediated gene upregulation. Our findings reveal an unexpected principle of miRNA-mediated gene regulation, and could impact the understanding of many miRNA-regulated biological processes.

bioinformatics↗

bioRxiv2019

Regeneration of dorsal spinal cord neurons after injury via in situ NeuroD1-mediated astrocyte-to-neuron conversion

Spinal cord injury (SCI) often leads to impaired motor and sensory functions, partially because the injury-induced neuronal loss cannot be easily replenished through endogenous mechanisms. In vivo neuronal reprogramming has emerged as a novel technology to regenerate neurons from endogenous glial cells by forced expression of neurogenic transcription factors. We have previously demonstrated successful astrocyte-to-neuron conversion in mouse brains with injury or Alzheimers disease by overexpressing a single neural transcription factor NeuroD1 via retroviruses. Here we demonstrate regeneration of dorsal spinal cord neurons from reactive astrocytes after SCI via adeno-associated virus (AAV), a more clinically relevant gene delivery system. We find that NeuroD1 converts reactive astrocytes into neurons in the dorsal horn of stab-injured spinal cord with high efficiency ([~]95%). Interestingly, NeuroD1-converted neurons in the dorsal horn mostly acquire glutamatergic neuronal subtype, expressing spinal cord-specific markers such as Tlx3 but not brain-specific markers such as Tbr1, suggesting that the astrocytic lineage and local microenvironment affect the cell fate of conversion. Electrophysiological recordings show that the NeuroD1-converted neurons can functionally mature and integrate into local spinal cord circuitry by displaying repetitive action potentials and spontaneous synaptic responses. We further show that NeuroD1-mediated neuronal conversion can occur in the contusive SCI model, allowing future studies of evaluating this reprogramming technology for functional recovery after SCI. In conclusion, this study may suggest a paradigm shift for spinal cord repair using in vivo astrocyte-to-neuron conversion technology to generate functional neurons in the grey matter.

neuroscience↗

bioRxiv2019

A virus-encoded protein suppresses methylation of the viral genome through its interaction with AGO4 in the Cajal body

In plants, establishment of de novo DNA methylation is regulated by the RNA-directed DNA methylation (RdDM) pathway. RdDM machinery is known to concentrate in the Cajal body, but the biological significance of this localization has remained elusive. Here, we show that the anti-viral methylation of the Tomato yellow leaf curl virus (TYLCV) genome occurs specifically in the Cajal body of Nicotiana benthamiana cells. Methylation of the viral genome is countered by a virus-encoded protein, V2, which interacts with the central RdDM component AGO4, interfering with its binding to the viral DNA; Cajal body localization of the V2-AGO4 interaction is required for the viral protein to exert this function. Taken together, our results draw a long sought-after functional connection between RdDM, the Cajal body, and anti-viral DNA methylation, paving the way for a deeper understanding of DNA methylation and anti-viral defences in plants.

plant biology↗

bioRxiv2019

Lineage-Specific Epigenomic and Genomic Activation of the Oncogene HNF4A Promotes Gastrointestinal Adenocarcinomas

BackgroundsGastrointestinal adenocarcinomas (GIACs) of the tubular GI tract including esophagus, stomach, colon and rectum comprise most GI cancers and share a spectrum of genomic features. However, the unified epigenomic changes specific to GIACs are less well-characterized.We applied mathematical algorithms to large-scale DNA methylome and transcriptome profiles to reconstruct transcription factor (TF) networks using 907 GIAC samples from The Cancer Genome Atlas (TCGA). Complementary epigenomic technologies were performed to investigate HNF4A activation, including Circularized Chromosome Conformation Capture (4C), Chromatin immunoprecipitation (ChIP) sequencing, Whole Genome Bisulfite Sequencing (WGBS), and Assay for Transposase-Accessible Chromatin (ATAC) sequencing. In vitro and in vivo cellular phenotypical assays were conducted to study HNF4A functions.\n\nResultsWe identified a list of functionally hyperactive master regulator (MR)TFs shared across different GIACs. As the top candidate, HNF4A exhibited prominent genomic and epigenomic activation in a GIAC-specific manner. We further characterized a complex interplay between HNF4A promoter and three distal enhancer elements, which was coordinated by GIAC-specific MRTFs including ELF3, GATA4, GATA6 and KLF5. HNF4A also self-regulated its own promoter and enhancers. Functionally, HNF4A promoted cancer proliferation and survival by transcriptionally activating many downstream targets including HNF1A and factors of Interleukin signaling in a lineage-specific manner.\n\nConclusionWe use a large cohort of patient samples and an unbiased mathematical approach to highlight lineage-specific oncogenic MRTFs, which provide new insights into the GIAC-specific gene regulatory networks, and identify potential therapeutic strategies against these common cancers.

cancer biology↗

bioRxiv2019

Genome-wide variations analysis of special waxy sorghum cultivar Hongyingzi for brewing Moutai liquor

AbstractsHongyingzi is a special waxy sorghum (Sorghum bicolor L. Moench) cultivar for brewing Moutai liquor. For an overall understanding of the whole genome of Hongyingzi, we performed whole-genome resequencing technology with 56.10 X depth to reveal its comprehensive variations. Compared with the BTx623 reference genome, 2.48% of genome sequences were altered in the Hongyingzi genome. Among these alterations, there were 1885774 single nucleotide polymorphisms (SNPs), 309381 small fragments insertions and deletions (Indels), 31966 structural variations (SVs), and 217273 copy number variations (CNVs). These alterations conferred 29614 genes variations. It was also predicted that 35 genes variations were related to the multidrug and toxic efflux (MATE) transporter, chalcone synthase (CHS), ATPase isoform 10 (AHA10) transporter, dihydroflavonol-4-reductase (DFR), the laccase 15 (LAC15), flavonol 3'-hydroxylase (F3'H), flavanone 3-hydroxylase (F3H), O-methyltransferase (OMT), flavonoid 3'5' hydroxylase (F3'5'H), UDP-glucose:sterol-glucosyltransferase (SGT), flavonol synthase (FLS), and chalcone isomerase (CHI) involved in the tannin synthesis. These results would provide theoretical supports for the molecular markers developments and gene function studies related to the liquor-making traits, and the genetic improvement of waxy sorghum based on the genome editing technology.

genomics↗

bioRxiv2019

In Vivo Study of Key Transcription Factors in Muscle Satellite Cells by CRISPR/Cas9/AAV9-sgRNA Mediated Genome Editing

Skeletal muscle satellite cells (SCs) are adult muscle stem cells responsible for injury induced muscle regeneration. Despite advances in the knowledge of molecular mechanisms regulating SC lineage progression, our understanding of key transcription factors (TFs) and their regulatory functions in SCs in particularly the quiescent and early activation stages remains incomplete due to the lack of efficient method to screen and investigate the stage-specific key TFs. In this study, we succeeded in defining a distinct list of key TFs in early stages of SC fate transition using the paradigm of super enhancers (SEs). Particularly, leveraging the Cre-dependent Cas9 knockin mice and AAV9 mediated sgRNAs delivery, we generated a facile muscle specific genome editing system which allows gene depletion in SCs in vivo. Using MyoD locus as a proof of concept, we demonstrated that this CRISPR/Cas9/AAV9-sgRNA system can efficiently introduce mutagenesis at target locus and recapture the phenotypes reported in knockout mice. Further application of the system on key TFs, Myc, Bcl6 and Pknox2, revealed their distinct functions in the early stage of SC activation and damage induced muscle regeneration. Altogether our findings have proven the CRISPR/Cas9/AAV9-sgRNA system as a robust way for in vivo genome editing and elucidation of key factors governing SC activities.

genetics↗

bioRxiv2019

The maize heterotrimeric G-protein β subunit controls shoot meristem development and immune responses.

Heterotrimeric G-proteins are important transducers of receptor signaling, functioning in plants with CLAVATA receptors in control of shoot meristem size, and with pathogen associated molecular pattern (PAMP) receptors in basal immunity. However, whether specific members of the heterotrimeric complex potentiate crosstalk between development and defense, and the extent to which these functions are conserved across species, has not been addressed. Here we used CRISPR/Cas9 to knockout the maize G{beta} subunit gene, and found that the mutants were lethal, differing from Arabidopsis, where homologous mutants have normal growth and fertility. We show that lethality is not caused by a specific developmental arrest, but by autoimmunity. We used a genetic diversity screen to suppress the lethal g{beta} phenotype, and also identified a new maize G{beta} allele with weak autoimmune responses but strong development phenotypes. Using these tools, we show that G{beta} controls meristem size in maize, acting epistatically with G, suggesting that G{beta} and G function in a common signaling complex. Furthermore, we used an association study to show that natural variation in G{beta} influences maize kernel row number, an important agronomic trait. Our results demonstrate the dual role of G{beta} in immunity and development in a cereal crop, and suggest that it functions in crosstalk between these competing signaling networks. Therefore, modification of G{beta} has the potential to optimize the tradeoff between growth and defense signaling to improve agronomic production.\n\nSignificanceCereal crops, such as maize provide our major food and feed. Crop productivity has been significantly improved by selection of favorable architecture and development alleles, however crops are constantly under attack from pathogens, which severely limits yield due to a defense-growth tradeoff. Therefore, it is critical to identify key signaling regulators that control both developmental and immune signaling, to provide basic knowledge to maximize productivity. This work shows that the maize G protein {beta} subunit regulates both meristem development and immune signaling, and suggests that manipulation of this gene has the potential to optimize the tradeoff between yield and disease resistance to improve crop yields.

plant biology↗

bioRxiv2019

Saak Transform-Based Machine Learning for Light-Sheet Imaging of Cardiac Trabeculation

Recent advances in light-sheet fluorescence microscopy (LSFM) enable 3-dimensional (3-D) imaging of cardiac architecture and mechanics in toto. However, segmentation of the cardiac trabecular network to quantify cardiac injury remains a challenge. We hereby employed \"subspace approximation with augmented kernels (Saak) transform\" for accurate and efficient quantification of the light-sheet image stacks following chemotherapy-treatment. We established a machine learning framework with augmented kernels based on the Karhunen-Loeve Transform (KLT) to preserve linearity and reversibility of rectification. The Saak transform-based machine learning enhances computational efficiency and obviates iterative optimization of cost function needed for neural networks, minimizing the number of training data sets to three 2-D slices for segmentation in our scenario. The integration of forward and inverse Saak transforms serves as a light-weight module to filter adversarial perturbations and reconstruct estimated images, salvaging robustness of existing classification methods. The accuracy and robustness of the Saak transform are evident following the tests of dice similarity coefficients and various adversary perturbation algorithms, respectively. The addition of edge detection further allows for quantifying the surface area to volume ratio (SVR) of the myocardium in response to chemotherapy-induced cardiac remodeling. The combination of Saak transform, random forest, and edge detection augments segmentation efficiency by 20-fold as compared to manual processing; thus, establishing a robust framework for post light-sheet imaging processing, creating a data-driven machine learning for 3-D quantification of cardiac ultra-structure.

bioengineering↗

bioRxiv2019

Novel regulators of nitric oxide signaling triggered by host perception in a plant pathogen

The rhizosphere interaction between plant roots or pathogenic microbes is initiated by mutual exchange of signals. However, how soil pathogens sense host signals is largely unknown. Here, we studied early molecular events associated with host recognition in Fusarium graminearum, an economically important fungal pathogen that can infect both roots and heads of cereal crops. We found that host-sensing prior to physical contact with plant roots radically alters the transcriptome and triggers nitric oxide (NO) production in F. graminearum. We identified an ankyrin-repeat domain containing protein (FgANK1) required for host-mediated NO production and virulence in F. graminearum. In the absence of host plant, FgANK1 resides in the cytoplasm. In response to host signals, FgANK1 translocates to the nucleus and interacts with a zinc finger transcription factor (FgZC1), also required for NO production and virulence in F. graminearum. Our results reveal new mechanistic insights into host-recognition strategies employed by soil pathogens.

pathology↗

bioRxiv2019

SORBS2 is a susceptibility gene to arrhythmogenic right ventricular cardiomyopathy

BACKGROUNDArrhythogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy characterized by right ventricular remodeling and ventricular arrhythmia. To date, 16 ARVC causative genes have been identified from human genetic studies, accounting for about 60% of ARVC probands. Genetic basis for the remaining 40% ARVC probands remain elusive.\n\nMETHODSPrompted by a zebrafish mutagenesis screen that suggested the Sorbin and SH3 domain-containing 2 (SORBS2) ortholog as a candidate cardiomyopathy gene, we conducted detailed expressionl analysis of Sorbs2 in mice, as well as phenotypic characterization in the Sorbs2 knock-out (KO) mice. The intercalated disc (ICD) expression pattern and ARVC-like phenotypes further prompted us to conduct targeted sequencing of human patients with ARVC to search for rare variants in the SORBS2 gene.\n\nRESULTSSorbs2 is robustly expressed in the mouse heart, encoding an adhesion junction/desmosome protein that is mainly localized to the ICD. A mutation with near complete depletion of the Sorbs2 protein in mouse results in phenotypes characteristic of human ARVC, such as dilated right ventricle (RV), RV dysfunction, spontaneous ventricular tachycardia (VT), and premature death. Sorbs2 is required to maintain the structural integrity of ICD. Its absence resulted in profound cardiac electrical remodeling with impaired impulse conduction and action potential derangements. Five rare variants were identified from a cohort of 59 ARVC patients, among which two variants affect splicing.\n\nCONCLUSIONSSorbs2 KO mouse is an ARVC model and SORBS2 is a new ARVC susceptibility gene.

genetics↗

bioRxiv2019

MAP2 is Hyperphosphorylated in Schizophrenia and Alters its Function

Schizophrenia (Sz) is a highly polygenic disorder, with common, rare, and structural variants each contributing only a small fraction of overall disease risk. Thus, there is a need to identify downstream points of convergence that can be targeted with therapeutics. Reduction of Microtubule-associated Protein 2 (MAP2) immunoreactivity (MAP2-IR) is present in individuals with Sz, despite no change in MAP2 protein levels. MAP2 is phosphorylated downstream of multiple receptors and kinases identified as Sz risk genes, altering its immunoreactivity and function. Using an unbiased phosphoproteomics approach we quantified 18 MAP2 phosphopeptides, 9 of which were significantly altered in Sz subjects. Network analysis grouped MAP2 phosphopeptides into 3 modules, each with a distinct relationship to dendritic spine loss, synaptic protein levels, and clinical function in Sz subjects. We then investigated the most hyperphosphorylated site in Sz, phosphoserine1782 (pS1782). Computational modeling predicted phosphorylation of S1782 reduces binding of MAP2 to microtubules, which was confirmed experimentally. We generated a transgenic mouse containing a phosphomimetic mutation at S1782 (S1782E) and found reductions in basilar dendritic length and complexity along with reduced spine density. Because only a limited number of MAP2 interacting proteins have been previously identified, we combined co-immunoprecipitation with mass spectrometry to characterize the MAP2 interactome in mouse brain. The MAP2 interactome was enriched for proteins involved in protein translation. These associations were shown to be functional as overexpression of wildtype and phosphomimetic MAP2 reduced protein synthesis in vitro. Finally, we found that Sz subjects with low MAP2-IR had reductions in the levels of synaptic proteins relative to nonpsychiatric control (NPC) subjects and to Sz subjects with normal and MAP2-IR, and this same pattern was recapitulated in S1782E mice. These findings suggest a new conceptual framework for Sz - that a large proportion of individuals have a "MAP2opathy" - in which MAP function is altered by phosphorylation, leading to impairments of neuronal structure, synaptic protein synthesis, and function.

neuroscience↗

bioRxiv2019

Expectation pooling: An effective and interpretable pooling method for predicting DNA-protein binding

MotivationConvolutional neural networks (CNNs) have outperformed conventional methods in modeling the sequence specificity of DNA-protein binding. While previous studies have built a connection between CNNs and probabilistic models, simple models of CNNs cannot achieve sufficient accuracy on this problem. Recently, some methods of neural networks have increased performance using complex neural networks whose results cannot be directly interpreted. However, it is difficult to combine probabilistic models and CNNs effectively to improve DNA-protein binding predictions.\n\nResultsIn this paper, we present a novel global pooling method: expectation pooling for predicting DNA-protein binding. Our pooling method stems naturally from the EM algorithm, and its benefits can be interpreted both statistically and via deep learning theory. Through experiments, we demonstrate that our pooling method improves the prediction performance DNA-protein binding. Our interpretable pooling method combines probabilistic ideas with global pooling by taking the expectations of inputs without increasing the number of parameters. We also analyze the hyperparameters in our method and propose optional structures to help fit different datasets. We explore how to effectively utilize these novel pooling methods and show that combining statistical methods with deep learning is highly beneficial, which is promising and meaningful for future studies in this field.\n\nContactdengmh@pku.edu.cn, gaog@mail.cbi.pku.edu.cn\n\nSupplementary informationAll code is public in https://github.com/gao-lab/ePooling

bioinformatics↗

bioRxiv2019

Dosage effect of multiple genes accounts for multisystem disorder of myotonic dystrophy type 1

Multisystem manifestations in myotonic dystrophy type 1 (DM1) may be due to dosage reduction in multiple genes induced by aberrant expansion of CTG repeats in DMPK, including Dmpk and its neighboring genes (Six5 or Dmwd) and downstream Mbnl1. However, the direct evidences are lack. Here, we develop a new strategy to generate mice carrying multigene mutations in one step by injection of haploid embryonic stem cells with mutant Dmpk, Six5 and Mbnl1 into oocytes. The triple heterozygous mutant mice exhibit adult-onset DM1 phenotypes. With the additional mutation in Dmwd, quadruple heterozygous mutant mice recapitulate many major manifestations in congenital DM1. Moreover, muscle stem cells in both models display reduced stemness. Our results suggest that the complex symptoms of DM1 result from the reduced gene dosage of multiple genes.

genetics↗

bioRxiv2019

Synaptic Proteome Alterations in the Primary Auditory Cortex of Schizophrenia

ImportanceFindings from unbiased genetic studies have consistently implicated synaptic protein networks in Schizophrenia (Sz), but the molecular pathology at these networks and their potential contribution to the synaptic and circuit deficits thought to underlie disease symptoms remain unknown.\n\nObjectiveTo determine if protein levels are altered within synapses from primary auditory cortex (A1) of subjects with Sz; and if so, are these differences restricted to the synapse or present throughout the grey matter?\n\nDesignA paired case-control design was utilized for this study. Biochemical fractional - targeted Mass Spectrometry (MS) was used to measure the levels of >350 proteins in A1 grey matter homogenate and synaptosome preparations, respectively. All experimenters were blinded to diagnosis at every stage of sample preparation, MS analysis, and raw data processing. The effects of postmortem interval (PMI) and antipsychotic drug treatment on protein levels were assessed in mouse and monkey models, respectively.\n\nSettingAll cases were recruited from a single site, The Allegheny County Office of the Medical Examiner, and all tissues were processed at the University of Pittsburgh.\n\nParticipantsBrain specimens from all subjects were obtained during autopsies conducted at the Allegheny County Office of the Medical Examiner after receiving consent from the next-of-kin. An independent panel of experienced clinicians made consensus Diagnostic and Statistical Manual of Mental Disorders Fourth Edition diagnoses. Unaffected comparison subjects underwent identical assessments and were determined to be free of lifetime psychiatric illness. Each Sz subject was matched by sex, and as closely as possible for age and PMI, with one unaffected comparison subject.\n\nMain Outcomes and MeasuresPrimary measures were homogenate and synaptosome protein levels and their co-regulation network features. Prior to data collection we hypothesized: 1. That levels of canonical postsynaptic proteins in A1 synaptosome preparations would differ between Sz and control subjects; and 2. That these differences would not be explained by changes in total A1 homogenate protein levels.\n\nResultsMean subject age was 48 years for both groups with a range of 17-83; each group included 35 males and 13 females; mean PMI was 17.7 hours in controls and 17.9 in Sz. We observed robust alterations (q < 0.05) in synaptosome levels of canonical mitochondrial and postsynaptic proteins that were highly co-regulated and not readily explained by postmortem interval, antipsychotic drug treatment, synaptosome yield, or underlying alterations in homogenate protein levels.\n\nConclusions and RelevanceOur findings indicate a robust and highly coordinated rearrangement of the synaptic proteome likely driven by aberrant synaptic, not cell-wide, proteostasis. In line with unbiased genetic findings, our results identified alterations in synaptic levels of postsynaptic proteins, providing a road map to identify the specific cells and circuits that are impaired in Sz A1.

neuroscience↗

bioRxiv2019

The Vertebrate Codex Gene Breaking Protein Trap Library For Genomic Discovery and Disease Modeling Applications

The zebrafish is a powerful model to explore the molecular genetics and expression of the vertebrate genome. The gene break transposon (GBT) is a unique insertional mutagen that reports the expression of the tagged member of the proteome while generating Cre-revertible genetic alleles. This 1000+ locus collection represents novel codex expression data from the illuminated mRFP protein trap, with 36% and 87% of the cloned lines showcasing to our knowledge the first described expression of these genes at day 2 and day 4 of development, respectively. Analyses of 183 molecularly characterized loci indicate a rich mix of genes involved in diverse cellular processes from cell signaling to DNA repair. The mutagenicity of the GBT cassette is very high as assessed using both forward and reverse genetic approaches. Sampling over 150 lines for visible phenotypes after 5dpf shows a similar rate of discovery of embryonic phenotypes as ENU and retroviral mutagenesis. Furthermore, five cloned insertions were in loci with previously described phenotypes; embryos homozygous for each of the corresponding GBT alleles displayed strong loss of function phenotypes comparable to published mutants using other mutagenesis strategies (ryr1b, fras1, tnnt2a, edar and hmcn1). Using molecular assessment after positional cloning, to date nearly all alleles cause at least a 99+% knockdown of the tagged gene. Interestingly, over 35% of the cloned loci represent 68 mutants in zebrafish orthologs of human disease loci, including nervous, cardiovascular, endocrine, digestive, musculoskeletal, immune and integument systems. The GBT protein trapping system enabled the construction of a comprehensive protein codex including novel expression annotation, identifying new functional roles of the vertebrate genome and generating a diverse collection of potential models of human disease.

genomics↗

bioRxiv2019

From isochorismate to salicylate: a new reaction mechanism for salicylic acid biosynthesis

The phytohormone salicylic acid (SA) is a central regulator of plant immunity. Despite such functional importance, our knowledge of its biosynthesis is incomplete. Previous work showed that SA is synthesized from chorismic acid in plastids. The bulk of pathogen-induced SA derives from isochorismate generated by the catalytic activity of ISOCHORISMATE SYNTHASE1 (ICS1). How and in which cellular compartment isochorismate is converted to SA is unknown. Here we show that the pathway downstream of isochorismate requires only two additional proteins: the plastidial isochorismate exporter ENHANCED DISEASE SUSCEPTIBILITY5 (EDS5) and the cytosolic amido-transferase AvrPphB SUSCEPTIBLE3 (PBS3). PBS3 catalyzes the conjugation of glutamate to isochorismate. The reaction product isochorismate-9-glutamate spontaneously decomposes into enolpyruvyl-N-glutamate and SA. This previously unknown reaction mechanism appears to be conserved throughout the plant kingdom.\n\nOne Sentence SummarySalicylic acid is synthesized via isochorismate-9-glutamate by PBS3.

plant biology↗