Biology subjects

Shao, Y.

Publications and source records attributed to Shao, Y..

At least 91 records · Page 5Linked to original sources

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

Invasiveness of Cancer Populations in a Two-dimensional Percolation cluster: a Stochastic Mathematical Approach

A framework for the software Unstructured Reaction-Diffusion Master Equation (URDME) was developed. A mitogenic paracrine signaling pathway was introduced phenomenologically to show how cells cooperate with one another. We modeled the emerging Allee effect using low seeding density culture (LSDC) assays to fit the model parameters. Finite time scaling (FTS) was found to be a useful tool for quantifying invasiveness in cancer populations. Through simulation, we analyzed the growth-migration dynamics of BT474 cancer cell populations in-vitro in a 2D percolation cluster and calculated the SPR (successful penetration rate). By analyzing the temporal trajectories of the SPR, we could determine the critical exponents of the critical SPR scaling relation [Formula]. Moreover, the SPR transition point defined according to the FTS theory, Pc, is negatively correlated with the invasiveness of cancer cell populations. The Pc of the three virtual cancer populations distinctly designated by varying the parameter set of the same model are 0.3408, 0.3675, and 0.4454, respectively. Therefore, the FTS algorithm may be useful in determining invasiveness. Through the simplistic phenomenological paracrine model, inter-cell cooperation and mutual mitogenic boosting are enabled, causing the Allee effect to occur. Such a method could be applied to other circumstances as an example of the quantitatively falsifiable emerging theory.

cancer biology↗

bioRxiv2022

Multi-omic analysis along the gut-brain axis points to a functional architecture of autism

Autism is a highly heritable neurodevelopmental disorder characterized by heterogeneous cognitive, behavioral and communication impairments. Disruption of the gut-brain axis (GBA) has been implicated in autism, with dozens of cross-sectional microbiome and other omic studies revealing autism-specific profiles along the GBA albeit with little agreement in composition or magnitude. To explore the functional architecture of autism, we developed an age and sex-matched Bayesian differential ranking algorithm that identified autism-specific profiles across 10 cross-sectional microbiome datasets and 15 other omic datasets, including dietary patterns, metabolomics, cytokine profiles, and human brain expression profiles. The analysis uncovered a highly significant, functional architecture along the GBA that encapsulated the overall heterogeneity of autism phenotypes. This architecture was determined by autism-specific amino acid, carbohydrate and lipid metabolism profiles predominantly encoded by microbial species in the genera Prevotella, Enterococcus, Bifidobacterium, and Desulfovibrio, and was mirrored in brain-associated gene expression profiles and restrictive dietary patterns in individuals with autism. Pro-inflammatory cytokine profiling and virome association analysis further supported the existence of an autism-specific architecture associated with particular microbial genera. Re-analysis of a longitudinal intervention study in autism recapitulated the cross-sectional profiles, and showed a strong association between temporal changes in microbiome composition and autism symptoms. Further elucidation of the functional architecture of autism, including of the role the microbiome plays in it, will require deep, multi-omic longitudinal intervention studies on well-defined stratified cohorts to support causal and mechanistic inference.

microbiology↗

bioRxiv2022

NSD2 E1099K drives relapse in pediatric acute lymphoblastic leukemia by disrupting 3D chromatin organization

The NSD2 p.E1099K (EK) mutation has been shown to be enriched in patients with relapsed ALL and found to play a role in clonal fitness dependent on the underlying genetic/epigenetic landscape of the cells. To uncover 3D chromatin architecture-related mechanisms underlying drug resistance, we systematically integrated Hi-C, ATAC-seq, RNA-seq and ChIP-seq data from three B-ALL cell lines heterozygous for NSD2 EK (RS4;11, RCH-ACV, SEM) and assessed changes upon knockdown. NSD2 knockdown revealed widespread remodeling of the 3D genome, specifically in terms of compartmentalization. Systematic integration of these datasets revealed significant switches in A/B compartments with a strong bias towards B compartments upon knockdown, suggesting that NSD2 EK plays a prominent role in maintaining A compartments through enrichment of H3K36me2 epigenetic marks. In contrast, we identified few changes in intra-TAD activity suggesting that the NSD2 EK impacts transcriptional changes through a remarkable dependence on compartmentalization. Furthermore, EK-mediated reorganization of compartments highlights the existence of a common core of compacting loci shared across the three cell lines that explain previously described phenotypes as well as serve as targets for therapeutic intervention. This study offers a novel mechanism by which NSD2 EK drives clonal evolution and drug resistance.

cancer biology↗

bioRxiv2022

In vitro demonstration of broad host range mobile genetic elements transferring antibiotic resistance from the human microbiome

Mobile genetic elements (MGEs) carrying antibiotic resistance genes (ARGs) disseminate ARGs when they mobilise into new bacterial hosts. To investigate the scale of such horizontal gene transfer (HGT) events between human gut commensals and enteropathogens for the first time, we compared 1354 cultured commensal strains (540 species) to 45,403 enteropathogen strains (12 species) and found 64,188 MGE-mediated ARG transfer events between the two groups using established methods. Among the 5931 MGEs involved, we found 15 broad host range elements predicted to have crossed different bacterial phyla while also occurring in animal and environmental microbiomes. We experimentally demonstrated that predicted broad host range MGEs can mobilise from commensals Dorea longicatena and Hungatella hathewayi to enteropathogens Klebsiella oxytoca, crossing phyla simultaneously. Our work establishes the MGE-mediated ARG dissemination network between human gut commensals and enteropathogens and highlights novel broad host range MGEs as targets for future ARG dissemination management.

genomics↗

bioRxiv2021

Deactivation of SARS-CoV-2 surrogate porcine epidemic diarrhea virus with electron beam irradiation under the cold chain transportation condition

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has prevailed all over the world and emerged as a significant public health emergency. The rapid outbreak of SARS-CoV-2 is largely due to its high transmission capacity. Studies implied that the cold chain logistics would be a potential route for the spread of SARS-CoV-2. The low temperature condition of the cold chain is conducive to survival and transmission of virus. Thus, the virus disinfection in cold chain should not be neglected for controlling COVID-19. However, due to the low temperature feature of the cold-chain, the virus disinfecting methods suitable in cold chain are limited. Here the high-energy electron beam irradiation is proposed to disinfect the SARS-CoV-2 in cold chain logistics. We evaluated the impact of high-energy electron beam irradiation on porcine epidemic diarrhea virus (PEDV), an enveloped virus surrogate for SARS-CoV-2, and explored the possible mechanism of the action of high-energy electron beam irradiation on PEDV. The irradiation dose of 10 kGy inactivated 98.1 % PEDV on the both top and bottom surfaces of various packaging materials under cold chain frozen condition. High-energy electron beam inactivated PEDV by inducing damages on viral genome or even capsid.

microbiology↗

bioRxiv2021

Peripheral sTREM2-related inflammatory activity alterations in early stage Alzheimer's disease

Alzheimers disease (AD) has been linked to multiple immune system genetic variants, implicating potential broad alterations in inflammatory profiles in the disease. Triggering receptor expressed on myeloid cells 2 (TREM2) genetic variants are risk factors for AD and other neurodegenerative diseases. A soluble TREM2 isoform (sTREM2) is elevated in cerebrospinal fluid in the early stages of AD suggesting it may be a biomarker of progressive alterations in immune response to AD-related pathology. Multiple studies have reported an altered peripheral immune response in AD. However, less is known about the relationship between plasma sTREM2 and the altered peripheral immune response in AD. The objective of this exploratory study was to examine the relationship between sTREM2 and inflammatory activity in human participants defined by clinically characterized cognitive symptoms and groups defined by the cerebrospinal fluid biomarkers amyloid beta, phosphorylated tau, and neurodegeneration (NIA-AA Research Framework: "ATN continuum".) The hypothesis of this exploratory study was that sTREM2 related inflammatory activity differs by AD stage. We observed different patterns of inflammatory activity across disease groups and ATN categories that implicates peripheral sTREM2 related inflammatory activity as altered in the early stages of AD. Notably, fractalkine showed a significant relationship with sTREM2 across different analyses in the control groups that was lost as disease progressed, and fractalkine, IL-5 and IL-17A were decreased in AD. These preliminary data provide important support to the hypothesis that sTREM2-related inflammatory activity is a stage-specific biomarker of AD progression, providing the groundwork for future studies and therapeutic strategies.

neuroscience↗

bioRxiv2021

Radiosynthesis and preclinical evaluation of a carbon-11 labeled PDE7 inhibitor for PET neuroimaging

BackgroundDysfunction of cyclic nucleotide phosphodiesterase 7 (PDE7) has been associated with excess intracellular cAMP concentrations, fueling pathogenic processes that are implicated in neurodegenerative disorders. The aim of this study was to develop a suitable PDE7-targeted positron emission tomography (PET) probe that allows non-invasive mapping of PDE7 in the mammalian brain. MethodsBased on a spiro cyclohexane-1,4-quinazolinone scaffold with known inhibitory properties towards PDE7, we designed and synthesized a methoxy analog that was suitable for carbon-11 labeling. Radiosynthesis was conducted with the respective desmethyl precursor using [11C]MeI. The resulting PET probe, codenamed [11C]26, was evaluated by cell uptake studies, ex vivo biodistribution and radiometabolite studies, as well as in vivo PET experiments in rodents and nonhuman primates (NHP). ResultsTarget compound 26 and the corresponding phenolic precursor were synthesized in 2-3 steps with overall yields of 49.5% and 12.4%, respectively. An inhibitory constant (IC50) of 31 nM towards PDE7 was obtained and no significant interaction with other PDE isoforms were observed. [11C]26 was synthesized in high molar activities (170 - 220 GBq/{micro}mol) with radiochemical yields of 34{+/-}7%. In vitro cell uptake of [11C]26 was 6-7 folds higher in PDE7 overexpressing cells, as compared to the controls, whereas an in vitro specificity of up to 90% was measured. Ex vivo metabolite studies revealed a high fraction of intact parent in the rat brain (98% at 5 min and 75% at 30 min post injection). Considerable brain penetration was further corroborated by ex vivo biodistribution and PET imaging studies - the latter showing heterogenic brain uptake. While marginal specific binding was observed by PET studies in rodents, a moderate, but dose-dependent, blockade was observed in the NHP brain following pretreatment with non-radioactive 26. ConclusionIn this work, we report on the preclinical evaluation of [11C]26 (codename [11C]P7-2104), a PDE7-targeted PET ligand that is based on a spiroquinazolinone scaffold. [11C]26 displayed promising in vitro performance characteristics, a moderate degree of specific binding in PET studies with NHP. Accordingly, [11C]26 will serve as a valuable lead compound for the development of a new arsenal of PDE7-targeted probes with potentially improved in vivo specificity.

neuroscience↗

bioRxiv2021

Amelioration of hemophilia B through CRISPR/Cas9 induced homology-independent targeted integration

Site-specific integration of exogenous gene through genome editing is a promising strategy for gene therapy. However, homology-directed repair (HDR) only occurring in proliferating cells is inefficient especially in vivo. To investigate the efficacy of Cas9-induced homology-independent targeted integration (HITI) strategy for gene therapy, a rat hemophilia B model was generated and employed. Through HITI, a DNA sequence encoding the last exon of rat Albumin (rAlb) gene fused with a high-specific-activity Factor IX variant (R338L) using T2A, was inserted into the last intron of rAlb via recombinant adeno-associated viral (rAAV). The knock-in efficiency reached up to 3.66% determined by ddPCR. The clotting time was reduced to normal level 4 weeks after treatment, and the circulating FIX level was gradually increased up to 52% of normal during 9 months even after partial hepatectomy, demonstrating the amelioration of hemophilia. Through PEM-seq, no significant off-targeting effect was detected. Moreover, this study provides a promising therapeutic approach for hereditary diseases.

bioengineering↗

bioRxiv2021

Development of a Triazolobenzodiazepine-Based PET Probe for Subtype-Selective Vasopressin 1A Receptor Imaging

ObjectivesTo enable non-invasive real-time quantification of vasopressin 1A (V1A) receptors in peripheral organs, we sought to develop a suitable PET probe that would allow specific and selective V1A receptor imaging in vitro and in vivo. MethodsWe synthesized a high-affinity and -selectivity ligand, designated compound 17. The target structure was labeled with carbon-11 and tested for its utility as a V1A-targeted PET tracer by cell uptake studies, autoradiography, in vivo PET imaging and ex vivo biodistribution experiments. ResultsCompound 17 (PF-184563) and the respective precursor for radiolabeling were synthesized in an overall yield of 49% (over 7 steps) and 40% (over 8 steps), respectively. An inhibitory constant of 0.9 nM towards the V1A receptor was measured, while excellent selectivity over the related V1B, V2 and OT receptor (IC50 >10,000 nM) were obtained. Cell uptake studies revealed considerable V1A binding, which was significantly reduced in the presence of V1A antagonists. Conversely, there was no significant blockade in the presence of V1B and V2 antagonists. In vitro autoradiography and PET imaging studies in rodents indicated specific tracer binding mainly in the liver. Further, the pancreas, spleen and the heart exhibited specific binding of [11C]17 ([11C]PF-184563) by ex vivo biodistribution experiments. ConclusionWe have developed the first V1A-targeted PET ligand that is suitable for subtype-selective receptor imaging in peripheral organs including the liver, heart, pancreas and spleen. Our findings suggest that [11C]PF-184563 can be a valuable tool to study the role of V1A receptors in liver diseases, as well as in cardiovascular pathologies.

pharmacology and toxicology↗

bioRxiv2020

Single-cell Individual Complete mtDNA Sequencing Uncovers Hidden Mitochondrial Heterogeneity in Human and Mouse Oocytes

The ontogeny and dynamics of mtDNA heteroplasmy remain unclear due to limitations of current mtDNA sequencing methods. We developed individual Mitochondrial Genome sequencing (iMiGseq) of full-length mtDNA for ultra-sensitive variant detection, complete haplotyping, and unbiased evaluation of heteroplasmy levels, all at the individual mtDNA molecule level. iMiGseq uncovers unappreciated levels of heteroplasmic variants in single healthy human oocytes well below the current 1% detection limit, of which numerous variants are detrimental and could contribute to late-onset mitochondrial disease and cancer. Extreme mtDNA heterogeneity among oocytes of the same mouse female, and a strong selection against deleterious mutations in human oocytes are observed. iMiGseq could comprehensively characterize and haplotype single-nucleotide and structural variants of mtDNA and their genetic linkage in NARP/Leigh syndrome patient-derived cells. Therefore, iMiGseq could not only elucidate the mitochondrial etiology of diseases, but also help diagnose and prevent mitochondrial diseases with unprecedented precision.

genomics↗

bioRxiv2020

Multiple Mechanisms of HIV-1 resistance to PGT135 in Chinese Subtype B' Slow Progressor

In our study, we describe a slow progressor CBJC515 from whom we constructed pseudoviruses expressing autologous Env. We surprisingly found all the pseudoviruses were resistant to PGT135. By making site-directed mutations and chimeric Env constructs, we found the early 05 strains escaped from PGT135 by losing the N332 glycan site, while the later 06 and 08 strains may escape with the retention of key epitopes through the change of V1/V4/C2 region or by N398/N611 glycan, which was selected as unique N-glycosylation site of CBJC515 compared with CBJC437 whose viruses were also harboring key epitopes but sensitive to PGT135. These findings provide insights into how HIV-1 can escape from N332-directed broadly neutralizing antibody (bNAb) responses without changing the epitope itself, and these ways may be useful to prolong the exposures of bNAb epitopes and contribute to bNAb development. Furthermore, our chimeric experiments also allowed us to explore the co-evolution and retention of functionality among regions. We confirmed that the V1V2 region has a wide range of effectiveness in interfering with the function of envelope protein and the V3 region can promote protein function recovery and buffer the harmful polymorphisms in the other regions contributing to the Env antigenic diversity. These results may provide some clues for the design of vaccines against HIV-1 strains. IMPORTANCEOur findings of mechanisms escaping from PGT135 verified the extensive role of long V1 region in mediating escape from V3-bNAbs. In addition, we also found multiple additional ways suggested that extreme variation may be needed by HIV-1 to escape from PGT135 without changing the epitope itself. Although the V3-glycan bNAb responses are among the most promising vaccine targets, as they are commonly elicited during infection, our findings indicated there may be additional difficulties to be taken into account in immunogen design, such as the consideration of other regions and some glycosylation sites affecting the mask of key epitopes, as well as the selection pressure that may be required by other bNAbs. Our chimeric experiment also highlighted the key role of V3 region in contributing to the maintenance of Env diversity by buffering deleterious polymorphisms, which may be helpful for vaccine design.

immunology↗

bioRxiv2020

ALC1 links chromatin accessibility to PARP inhibitor response in homologous recombination deficient cells

The response to Poly (ADP-ribose) polymerase inhibitors (PARPi) is dictated by homologous recombination (HR) DNA repair mechanisms and the abundance of lesions that trap PARP enzymes on chromatin. It remains unclear, however, if the established role of PARP in promoting chromatin accessibility impacts viability in these settings. Using a CRISPR based screen, we identify the PAR-binding Snf2-like ATPase, ALC1/CHD1L, as a key determinant of PARPi toxicity in HR-deficient cells. ALC1 loss reduced viability of BRCA mutant cells and enhanced their sensitivity to PARPi by up to 250-fold, while overcoming several known resistance mechanisms. ALC1 loss was not epistatic to other repair pathways that execute the PARPi response. Instead, ALC1 deficiency reduced chromatin accessibility concomitant with a decrease in the association of repair factors. This resulted in an accumulation of replication associated DNA damage and a reliance on HR. These findings establish PAR-dependent chromatin remodeling as a mechanistically distinct aspect of PARPi responses, implicating ALC1 inhibition as a new approach to overcome therapeutic resistance in HR-deficient cancers.

cancer biology↗

bioRxiv2020

New Genes in Drosophila Quickly Evolved Essential Functions in Viability During Development

It is a conventionally held dogma that the genetic basis underlying development is conserved in a long evolutionary time scale. Ample experiments based on mutational, biochemical, functional, and complementary knockdown/knockout approaches have revealed the unexpectedly important role of recently evolved new genes in the development of Drosophila. The recent progress in the analyses of gene effects and improvements in the computational identification of new genes, which has led to large sample sizes of new genes, open the door to investigate the evolution of gene essentiality with a phylogenetically high resolution. These advancements also raised interesting issues related to phenotypic effect analyses of genes, particularly of those that recently originated. Here we reported our analyses of these issues, including the dating of gene ages, the interpretation of RNAi data that may confuse false positive/false negative rates, and the potential confounding impact of compensation and developmental effects that were not considered during previous CRISPR knockout experiments. We further analyzed new data from knockdowns of 702 new genes (~66% of total 1,070 Drosophila melanogaster new genes), revealing a similarly high proportion of essential genes from recent evolution, compared to those found in distant ancestors of D. melanogaster. Knockout of a few young genes detected analogous essentiality. Furthermore, our experimentally determined distribution and comparison of knockdown efficiency in different RNAi libraries provided valuable data for general functional analyses of genes. Taken together, these data, along with an improved understanding of the phenotypic effect analyses of new genes, provide further evidence to the conclusion that new genes in Drosophila quickly evolved essential functions in viability during development.

developmental biology↗

bioRxiv2020

Apical-root apoplastic acidification affects cell-wall extensibility in wheat under salinity stress

Plant salt tolerance is closely associated with a high rate of root growth. Although root growth is governed by cell-wall and apoplastic pH, the relationship between these factors in the root elongation zone under salinity stress remains unclear. Here, we assess apoplastic pH, pH- and expansin-dependent cell-wall extensibility, and expansin expression in the root elongation zone of salt-sensitive (Yongliang-15) and -tolerant (JS-7) cultivars under salinity stress. A six-day 80 mM NaCl treatment significantly reduced apical-root apoplastic pH, from 6.2 to 5.3, in both cultivars. Using a pH-dependent cell-wall extensibility experiment, we found that, under 0 mM NaCl treatment, the optimal pH for cell-wall loosening was 6.0 in the salinity-tolerant cultivar and 4.6 in the salinity-sensitive cultivar. Under 80 mM treatment, a pH of 5.0 mitigated the cell-wall stiffness caused by salinity stress in the salinity-tolerant cultivar, but promoted cell-wall stiffening in the salinity-sensitive cultivar. These changes in pH-dependent cell-wall extensibility are consistent with differences in the root growth of two cultivars under salinity stress. Exogenous expansin application, and expansin expression experiments, we found that salinity stress altered expansin expression, differentially affecting cell-wall extensibility under pH 5.0 and 6.0. TaEXPA7 and TaEXPA8 induced cell-wall loosening at pH 5.0, whereas TaEXPA5 induced cell-wall loosening at pH 6.0. These results elucidate the relationship between expansin and cell-wall extensibility in the root elongation zone, with important implications for enhancing plant growth under salinity stress.

plant biology↗

bioRxiv2020

TREM2 alters the phagocytic, apoptotic and inflammatory response to Aβ42 in HMC3 cells

Alzheimers disease (AD) is characterized by the accumulation in the brain of extracellular amyloid {beta} (A{beta}) plaques as well as intraneuronal inclusions (neurofibrillary tangles) consisting of total tau and phosphorylated tau. Also present are dystrophic neurites, loss of synapses, neuronal death, and gliosis. AD genetic studies have highlighted the importance of inflammation in this disease by identifying several risk associated immune response genes, including TREM2. TREM2 has been strongly implicated in basic microglia function including, phagocytosis, apoptosis, and the inflammatory response to A{beta} in mouse brain and primary cells. These studies show that microglia are key players in the response to A{beta} and in the accumulation of AD pathology. However, details are still missing about which apoptotic or inflammatory factors rely on TREM2 in their response to A{beta}, especially in human cell lines. Given these previous findings our hypothesis is that TREM2 influences the response to A{beta} toxicity by enhancing phagocytosis and inhibiting both the BCL-2 family of apoptotic proteins and pro-inflammatory cytokines. A{beta}42 treatment of the human microglial cell line, HMC3 cells, was performed and TREM2 was overexpressed or silenced and the phagocytosis, apoptosis and inflammatory response were evaluated. Results indicate that a robust phagocytic response to A{beta} after 24 hours requires TREM2 in HMC3 cells. Also, TREM2 inhibits A{beta} induced apoptosis by activating the Mcl-1/Bim complex. TREM2 is involved in activation of IP-10, MIP-1a, and IL-8, while it inhibits FGF-2, VEGF and GRO. Taken together, TREM2 plays a role in enhancing the microglial functional response to A{beta} toxicity in HMC3 cells. This novel information suggests that therapeutic strategies that seek to activate TREM2 may not only enhance phagocytosis, but it may also inhibit beneficial inflammatory factors, emphasizing the need to define TREM2-related inflammatory activity in not only mouse models of AD, but also in human AD.

molecular biology↗

bioRxiv2020

Phytophthora sojae effector Avr1d functions as E2 competitor and inhibits ubiquitination activity of GmPUB13 to facilitate infection

Oomycete pathogens such as Phytophthora secrete a repertoire of effectors to host cells to manipulate host immunity and benefit infection. In this study, we found that an RxLR effector, Avr1d, promoted Phytophthora sojae infection in soybean hairy-roots. Using a yeast two-hybrid screen, we identified the soybean E3 ubiquitin ligase GmPUB13 as a host target for Avr1d. By co-immunoprecipitation, gel infiltration and ITC assays, we confirmed that Avr1d interacts with GmPUB13 both in vivo and in vitro. Furthermore, we found that Avr1d inhibits the E3 ligase activity of GmPUB13. The crystal structure of Avr1d in complex with GmPUB13 was solved and revealed that Avr1d occupies the binding site for E2 ubiquitin conjugating enzyme on GmPUB13. In line with this, Avr1d competed with E2 ubiquitin conjugating enzymes for GmPUB13 binding in vitro, thereby decreasing the E3 ligase activity of GmPUB13. Meanwhile, we found that inactivation of the ubiquitin ligase activity of GmPUB13 stabilized GmPUB13 by blocking GmPUB13 degradation. Silencing of GmPUB13 in soybean hairy-roots decreased P. sojae infection, suggesting that GmPUB13 acts as a susceptibility factor, negatively regulating soybean resistance against P. sojae. Altogether, this study highlights a novel virulence mechanism of Phytophthora effectors, by which Avr1d competes with E2 for GmPUB13 binding to repress the GmPUB13 E3 ligase activity and thereby stabilizing the susceptibility factor GmPUB13 to facilitate Phytophthora infection. This is the first study to unravel the structural basis for modulation of host targets by Phytophthora effectors and will be instrumental for boosting plant resistance breeding. Significance StatementUbiquitination acts as a crucial regulator in plant immunity. Accordingly, microbial pathogens secrete effectors to hijak host ubiquitination system. However, the molecular mechanisms by which microbial effectors modulate host ubiquitination system are not yet clear. Here, we found that the Phytophthora sojae effector Avr1d physically binds to the U-box type E3 ligase GmPUB13, a susceptibility factor in soybean. The crystal structure of Avr1d in complex with GmPUB13 revealed that Avr1d occupies the binding site in GmPUB13 for the E2 ubiquitin conjugating enzyme and competes with E2 for physical binding to GmPUB13. Avr1d stabilized GmPUB13 by suppressing the self-ubiquitination activity of GmPUB13 and thereby promoting Phytophthora infection. This study provides structural basis for modulation of host targets by Phytophthora effectors.

microbiology↗

bioRxiv2020

Altered small-world functional network topology in patients with optic neuritis: A resting- state fMRI study

PurposeThis study investigated changes in small-world topology and brain functional connectivity in patients with optic neuritis (ON) by resting-state functional magnetic resonance imaging (rs-fMRI) and based on graph theory. MethodsA total of 21 patients with ON (8 males and 13 females) and 21 matched healthy control subjects (8 males and 13 females) were enrolled at the First Affiliated Hospital of Nanchang University and underwent rs-fMRI. Data were preprocessed and the brain was divided into 116 regions of interest. Small-world network parameters and area under the integral curve (AUC) were calculated from pairwise brain interval correlation coefficients. Differences in brain network parameter AUCs between the 2 groups were evaluated with the independent sample t-test, and changes in brain connection strength between ON patients and control subjects were assessed by network-based statistical analysis. ResultsIn the sparsity range from 0.08 to 0.48, both groups exhibited small-world attributes. Compared to the control group, global network efficiency, normalized clustering coefficient, and small-world value were higher whereas the clustering coefficient value was lower in ON patients. There were no differences in characteristic path length, local network efficiency, and normalized characteristic path length between groups. In addition, ON patients had lower brain functional connectivity strength among the rolandic operculum, medial superior frontal gyrus, insula, median cingulate and paracingulate gyri, amygdala, superior parietal gyrus, inferior parietal gyrus, supramarginal gyrus, angular gyrus, lenticular nucleus, pallidum, superior temporal gyrus, cerebellum_Crus1_L, and left cerebellum_Crus6_L compared to the control group (P < 0.05). ConclusionThe brain network in ON has a small-world attributes but shows reduced and abnormal connectivity compared to normal subjects. These findings provide a further insight into the neural pathogenesis of ON and reveal specific fMRI findings that can serve as diagnostic and prognostic indices.

neuroscience↗