Biology subjects

Wang, H.-Y.

Publications and source records attributed to Wang, H.-Y..

At least 37 records · Page 2Linked to original sources

bioRxiv2023

VviWRKY10 and VviWRKY30 co-regulate powdery mildew resistance through modulating SA and ET-based defenses in grapevine

ABSRACTGrapevine is one of the most important economic fruit crops in the world. The widely cultivated grapevine (Vitis vinifera, Vvi) is susceptible to powdery mildew caused by Erysiphe necator. In this study, CRISPR-Cas9 was used to simultaneously knock out VviWRKY10 and VviWRKY30 encoding two transcription factors reported to be implicated in defense regulation. Fifty-three wrky10 (Vviwrky10 single mutant) transgenic plants and fifteen wrky10wrky30 (Vviwrky10Vviwrky30 double mutant) transgenic plants were generated. In a 2-year field evaluation of resistance to powdery mildew, the wrky10 showed strong resistance, while the wrky10wrky30 showed moderate resistance. Further analyses revealed that salicylic acid (SA) and reactive oxygen species (ROS) contents in the leaves of wrky10 and wrky10wrky30 were significantly increased, so did the ethylene (ET) content in the leaves of wrky10. The results from dual luciferase (DLUC) reporter assays, electrophoretic mobility shift assays (EMSA) and chromatin immunoprecipitation (ChIP)-qPCR assays demonstrated that VviWRKY10 could directly bind to the W-boxes in the promoter of VviEDS5-2, VviPR1, VviPR5 and VviRBOHD2 and inhibit their transcription, supporting its role as a negative regulator of SA-dependent defense. By contrast, VviWRKY30 could directly bind to the W-boxes in the promoter of VviACS3 and VviACS3L and promote their transcription, playing a positive role in ET production and ET-dependent defense. Moreover, VviWRKY10 and VviWRKY30 can bind to each others promoters and mutually inhibit each others transcription. Taken together, our results have revealed a complex mechanism of regulation by VviWRKY10 and VviWRKY30 for activation of measured and balanced defense responses against powdery mildew in grapevine. One-sentence summaryVviWRKY10 and VviWRKY30 play different roles in powdery mildew resistance through the salicylic acid and ethylene, respectively, and there is mutual inhibition between VviWRKY10 and VviWRKY30.

plant biology↗

bioRxiv2023

Cell Membranes Sustain Phospholipid Imbalance Via Cholesterol Asymmetry

Membranes are molecular interfaces that compartmentalize cells to control the flow of nutrients and information. These functions are facilitated by diverse collections of lipids, nearly all of which are distributed asymmetrically between the two bilayer leaflets. Most models of biomembrane structure and function often include the implicit assumption that these leaflets have similar abundances of phospholipids. Here, we show that this assumption is generally invalid and investigate the consequences of lipid abundance imbalances in mammalian plasma membranes (PM). Using quantitative lipidomics, we discovered that cytoplasmic leaflets of human erythrocyte membranes have >50% overabundance of phospholipids compared to exoplasmic leaflets. This imbalance is enabled by an asymmetric interleaflet distribution of cholesterol, which regulates cellular cholesterol homeostasis. These features produce unique functional characteristics, including low PM permeability and resting tension in the cytoplasmic leaflet that regulates protein localization. These largely overlooked aspects of membrane asymmetry represent an evolution of classic paradigms of biomembrane structure and physiology.

biophysics↗

bioRxiv2023

The pentameric complex is not required for vertical transmission of cytomegalovirus in seronegative pregnant rhesus macaques

Congenital cytomegalovirus (cCMV) infection is the leading infectious cause of neonatal neurological impairment but essential virological determinants of transplacental CMV transmission remain unclear. The pentameric complex (PC), composed of five subunits, glycoproteins H (gH), gL, UL128, UL130, and UL131A, is essential for efficient entry into non-fibroblast cells in vitro. Based on this role in cell tropism, the PC is considered a possible target for CMV vaccines and immunotherapies to prevent cCMV. To determine the role of the PC in transplacental CMV transmission in a non-human primate model of cCMV, we constructed a PC-deficient rhesus CMV (RhCMV) by deleting the homologues of the HCMV PC subunits UL128 and UL130 and compared congenital transmission to PC-intact RhCMV in CD4+ T cell-depleted or immunocompetent RhCMV-seronegative, pregnant rhesus macaques (RM). Surprisingly, we found that the transplacental transmission rate was similar for PC-intact and PC-deleted RhCMV based on viral genomic DNA detection in amniotic fluid. Moreover, PC-deleted and PC-intact RhCMV acute infection led to similar peak maternal plasma viremia. However, there was less viral shedding in maternal urine and saliva and less viral dissemination in fetal tissues in the PC-deleted group. As expected, dams inoculated with PC-deleted RhCMV demonstrated lower plasma IgG binding to PC-intact RhCMV virions and soluble PC, as well as reduced neutralization of PC-dependent entry of the PC-intact RhCMV isolate UCD52 into epithelial cells. In contrast, binding to gH expressed on the cell surface and neutralization of entry into fibroblasts by the PC-intact RhCMV was higher for dams infected with PC-deleted RhCMV compared to those infected with PC-intact RhCMV. Our data demonstrates that the PC is dispensable for transplacental CMV infection in our non-human primate model. One Sentence SummaryCongenital CMV transmission frequency in seronegative rhesus macaques is not affected by the deletion of the viral pentameric complex.

microbiology↗

bioRxiv2023

Relationship of maternal cytomegalovirus-specific antibody responses and viral load to vertical transmission risk following primary maternal infection in a rhesus macaque model

Cytomegalovirus (CMV) is the most common congenital infection and cause of birth defects worldwide. Primary CMV infection during pregnancy leads to a higher frequency of congenital CMV (cCMV) than maternal re-infection, suggesting that maternal immunity confers partial protection. However, poorly understood immune correlates of protection against placental transmission contributes to the current lack of an approved vaccine to prevent cCMV. In this study, we characterized the kinetics of maternal plasma rhesus CMV (RhCMV) viral load (VL) and RhCMV-specific antibody binding and functional responses in a group of 12 immunocompetent dams with acute, primary RhCMV infection. We defined cCMV transmission as RhCMV detection in amniotic fluid (AF) by qPCR. We then leveraged a large group of past and current primary RhCMV infection studies in late-first/early-second trimester RhCMV-seronegative rhesus macaque dams, including immunocompetent (n=15), CD4+ T cell-depleted with (n=6) and without (n=6) RhCMV-specific polyclonal IgG infusion before infection to evaluate differences between RhCMV AF-positive and AF-negative dams. During the first 3 weeks after infection, the magnitude of RhCMV VL in maternal plasma was higher in AF-positive dams in the combined cohort, while RhCMV glycoprotein B (gB)- and pentamer-specific binding IgG responses were lower magnitude compared to AF-negative dams. However, these observed differences were driven by the CD4+ T cell-depleted dams, as there were no differences in plasma VL or antibody responses between immunocompetent AF-positive vs AF-negative dams. Overall, these results suggest that levels of neither maternal plasma viremia nor humoral responses are associated with cCMV following primary maternal infection in healthy individuals. We speculate that other factors related to innate immunity are more important in this context as antibody responses to acute infection likely develop too late to influence vertical transmission. Yet, pre-existing CMV glycoprotein-specific and neutralizing IgG may provide protection against cCMV following primary maternal CMV infection even in high-risk, immunocompromised settings. Author summaryCytomegalovirus (CMV) is the most common infectious cause of birth defects globally, but we still do not have licensed medical interventions to prevent vertical transmission of CMV. We utilized a non-human primate model of primary CMV infection during pregnancy to study virological and humoral factors that influence congenital infection. Unexpectedly, we found that the levels virus in maternal plasma were not predictive of virus transmission to the amniotic fluid (AF) in immunocompetent dams. In contrast, CD4+ T cell depleted pregnant rhesus macaques with virus detected in AF had higher plasma viral loads than dams not showing placental transmission. Virus-specific antibody binding, neutralizing, and Fc-mediated antibody effector antibody responses were not different in immunocompetent animals with and without virus detectable in AF, but passively infused neutralizing antibodies and antibodies binding to key glycoproteins were higher in CD4+ T cell-depleted dams who did not transmit the virus compared to those that did. Our data suggests that the natural development of virus-specific antibody responses is too slow to prevent congenital transmission following maternal infection, highlighting the need for the development of vaccines that confer levels of pre-existing immunity to CMV-naive mothers that can prevent congenital transmission to their infants during pregnancy.

immunology↗

bioRxiv2023

Antagonistic pleiotropy plays an important role in governing the evolution and genetic diversity of SARS-CoV-2

Analyses of the genomic diversity of SARS-CoV-2 found that some sites across the genome appear to have mutated independently multiple times with frequency significantly higher than four-fold sites, which can be either due to mutational bias, i.e., elevated mutation rate in some sites of the genome, or selection of the variants due to antagonistic pleiotropy, a condition where mutations increase some components of fitness at a cost to others. To examine how different forces shaped evolution of SARS-CoV-2 in 2020-2021, we analyzed a large set of genome sequences (~ 2 million). Here we show that while evolution of SARS-CoV-2 during the pandemic was largely mutation-driven, a group of nonsynonymous changes is probably maintained by antagonistic pleiotropy. To test this hypothesis, we studied the function of one such mutation, spike M1237I. Spike I1237 increases viral assembly and secretion, but decreases efficiency of transmission in vitro. Therefore, while the frequency of spike M1237I may increase within hosts, viruses carrying this mutation would be outcompeted at the population level. We also discuss how the antagonistic pleiotropy might facilitate positive epistasis to promote virus adaptation and reconcile discordant estimates of SARS-CoV-2 transmission bottleneck sizes in previous studies.

evolutionary biology↗

bioRxiv2022

Multivalent Human Cytomegalovirus Glycoprotein B Nucleoside-Modified mRNA Vaccines Demonstrate a Greater Breadth in T cell but not Antibody Responses

Human cytomegalovirus (HCMV) remains the most common congenital infection and infectious complication in immunocompromised patients. The most successful HCMV vaccine to-date, an HCMV glycoprotein B (gB) subunit vaccine adjuvanted with MF59, achieved 50% efficacy against primary HCMV infection. A previous study demonstrated that gB/MF59 vaccinees were less frequently infected with HCMV gB genotype strains most similar to the vaccine strain than strains encoding genetically distinct gB genotypes, suggesting strain-specific immunity accounted for the limited efficacy. To determine whether vaccination with multiple HCMV gB genotypes could increase the breadth of anti-HCMV gB humoral and cellular responses, we immunized 18 female rabbits with monovalent (gB-1), bivalent (gB-1+gB-3), or pentavalent (gB-1+gB-2+gB-3+gB-4+gB-5) gB lipid nanoparticle-encapsulated nucleoside-modified RNA (mRNA-LNP) vaccines. The multivalent vaccine groups did not demonstrate higher magnitude or breadth of the IgG response to the gB ectodomain or cell-associated gB compared to that of monovalent vaccine. Also, the multivalent vaccines did not show an increase in the breadth of neutralization activity and antibody-dependent cellular phagocytosis against HCMV strains encoding distinct gB genotypes. Yet, peripheral blood mononuclear cell-derived T cell responses elicited by multivalent vaccines were of a higher magnitude compared to that of monovalent vaccinated animals against a vaccine-mismatched gB genotype at peak immunogenicity. Our data suggests that inclusion of multivalent gB antigens is beneficial to increase the magnitude of T cell response but not an effective strategy to increase the breadth of anti-HCMV gB antibody responses. Further studies are required to validate whether the multivalent gB mRNA vaccines could effectively increase the T cell response breadth.

immunology↗

bioRxiv2022

Rapid and accurate discrimination of Mycobacterium abscessus subspecies based on matrix-assisted laser desorption ionization-time of flight spectrum and machine learning

BackgroundMycobacterium abscessus complex (MABC) has been reported to cause considerable complicated infections. Subspecies identification of MABC is crucial for adequate treatment due to different antimicrobial resistance property amid the subspecies. However, long incubation days is needed for the traditional antibiotic susceptibility testing (AST) method. Effective antibiotics administration often delayed considerably and caused unfavorable outcomes. Thus, we proposed a novel and accurate method to identify subspecies and its potential antibiotics resistance, to guide clinical treatment within hours. MethodsSubspecies of the MABC isolates were determined by secA1, rpoB, and hsp65. AST was tested by using microdilution method, as well as sequencing of erm(41) and rrl genes. MALDI-TOF mass spectrometry (MS) spectra were analyzed. The informative peaks on MS spectra were detected by random forest (RF) importance. Machine learning (ML) algorithms were used to build models for classifying MABC subspecies based on MALDI-TOF spectrum. The models were developed and validated by nested five-fold cross-validation to avoid over-fitting. ResultsIn total, 102 MABC isolates (52 subspecies abscessus and 50 subspecies massiliense) were analyzed. Top informative peaks including m/z 6715, 4739, 2805, etc. were identified. RF model attained AUROC of 0.9166 (95% CI: 0.9072-0.9196) and outperformed other algorithms in discriminating subspecies abscessus from massiliense. ConclusionWe developed a MALDI-TOF based ML model for rapid and accurate MABC subspecies identification. The novel diagnostic tool would guide a more accurate and timely MABC subspecies-specific treatment.

microbiology↗

bioRxiv2022

Coupling of protein condensates to ordered lipid domains determines functional membrane organization

During T-cell activation, the transmembrane adaptor Linker of Activation of T-cells (LAT) forms biomolecular condensates with Grb2 and Sos1, facilitating signaling. LAT has also been associated with cholesterol-rich condensed lipid domains. However, the potential coupling between protein condensation and lipid phase separation and its role in organizing T-cell signaling were unknown. Here, we report that LAT/Grb2/Sos1 condensates reconstituted on model membranes can induce and template lipid domains, indicating strong coupling between lipid- and protein-based phase separation. Correspondingly, activation of T-cells induces protein condensates that associate with and stabilize raft-like membrane domains. Inversely, lipid domains nucleate and stabilize LAT protein condensates in both reconstituted and living systems. This coupling of lipid and protein assembly is functionally important, since uncoupling of lipid domains from cytoplasmic protein condensates abrogates T-cell activation. Thus, thermodynamic coupling between protein condensates and ordered lipid domains regulates the functional organization of living membranes. SUMMARYMembrane-associated protein condensates couple to ordered membrane domains to determine the functional organization of T-cell plasma membranes

cell biology↗

bioRxiv2022

Spatial and temporal origin of the third SARS-CoV-2 Outbreak in Taiwan

Since the first report of SARS-CoV-2 in December 2019, Taiwan has gone through three local outbreaks. Unlike the first two outbreaks, the spatial and temporal origin of the third outbreak (April 20 to November 5, 2021) is still unclear. We assembled and analyzed a data set of more than 6,000 SARS-CoV-2 genomes, including 300 from Taiwan and 5812 related sequences downloaded from GISAID as of 2021/12/08. We found that the third outbreak in Taiwan was caused by a single virus lineage belonging to Alpha (B.1.1.7) strain. This lineage, T-III (the third outbreak in Taiwan), carries a distinct genetic fingerprint, consisting of spike M1237I (S-M1237I) and three silent mutations, C5812T, C15895T, and T27869C. The T-III is closest to the sequences derived from Turkey on February 8, 2021. The estimated age of the most recent common ancestor (TMRCA) of T-III is March 23, 2021 (95% highest posterior density [HPD] February 24 - April 13, 2021), almost one month before the first three confirmed cases on April 20, 2021. The effective population size of the T-III showed approximately 20-fold increase after the onset of the outbreak and reached a plateau in early June 2021. Our results reconcile several unresolved observations, including the occurrence of two infection clusters at the same time without traceable connection and several airline pilots who were PCR negative but serum IgM-/IgG+ for SARS-CoV-2 in late April. Therefore, in contrast to the general notion that the third SARS-CoV-2 outbreak in Taiwan was sparked by two imported cases from USA on April 20, 2021, which, in turn, was caused by the partial relaxation of entry quarantine measures in early April 2021, our comprehensive analyses demonstrated that the outbreak was most likely originated from Europe in February 2021.

evolutionary biology↗

bioRxiv2022

Targeting Reductive Metabolic Shifts by T315I Mutation in BCR-ABL Myeloid Leukemia for Therapy

T315I mutation of Bcr-Abl in chronic myeloid leukemia (CML) leads to therapeutic resistance. It is known that Bcr-Abl transformation causes ROS-induced DNA damages and replication stress, which can be exploited for anti-nucleotide therapy. We developed a small compound, JMF4073, which inhibited pyrimidylate kinases and selectively eliminated Bcr-Abl-transformed, but not untransformed myeloid cells, due to dTTP exhaustion and ROS-induced replication stress. However, T315I-Bcr-Abl-transformed cells were less vulnerable to JMF4073 because of higher dTTP pool and low replication stress. Unlike WT-Bcr-Abl-transformed cells, T315I-Bcr-Abl cells lacked Sirt1- regulated OXPHOS with increased glutamine flux to reductive carboxylation in TCA cycle and glutathione synthesis. Blocking mitochondrial pyruvate carrier (MPC) by UK-5099 reduced NADH and glutathione levels with replication stress induction, thereby converting T315I-Bcr-Abl cells sensitive to JMF4073 with dTTP and dCTP depletion. The combination of JMF4073 with UK-5099 showed in vivo eradication of T315I-Bcr-Abl-CML. These data reveal that T315I mutation causes reductive metabolic shifts in Bcr-Abl-CML, and demonstrate the therapeutic option by co-targeting MPC and pyrimidylate kinases.

cancer biology↗

bioRxiv2022

An E3 ligase network engages GCN1 to promote elongation factor-1α degradation on stalled ribosomes

How cells monitor the status of translating ribosomes is a major question in gene regulation. Elongating ribosomes frequently stall during mRNA translation, resulting in context- dependent activation of quality control pathways. However, surveillance mechanisms that specifically respond to stalled ribosomes with an elongation factor occupying the GTPase center have not been identified. By employing ternatin-4, an allosteric elongation factor-1 (eEF1A) inhibitor, we unveil an E3 ligase network that triggers ubiquitination and degradation of eEF1A on stalled ribosomes. A CRISPRi screen revealed two E3 ligases of unknown function, RNF14 and RNF25, which are both essential for ternatin-induced eEF1A degradation. Based on quantitative proteomics analysis, we find that RNF14 and RNF25 promote ubiquitination of eEF1A and a discrete set of ribosomal proteins. By forming a complex with RNF14, the ribosome collision sensor GCN1 plays an essential role in eEF1A degradation. Our findings illuminate a translation elongation checkpoint that monitors the ribosomal GTPase center.

cell biology↗

bioRxiv2022

Functional characterization of a neuropeptide receptor exogenously expressed in Aplysia neurons

Neuropeptides act mostly on a class of G-protein coupled receptors, and play a fundamental role in the functions of neural circuits underlying behaviors. However, the functions of neuropeptide receptors are poorly understood. Here, we used the mollusc model system Aplysia and microinjected the exogenous neuropeptide receptor apATRPR (Aplysia Allatotropin-related peptide receptor) with an expression vector (pNEX3) into Aplysia neurons that did not express the receptor. Physiological experiments demonstrated that apATRPR could mediate the excitability increase activated by its ligand, apATRP (Aplysia Allatotropin-related peptide), in the Aplysia neurons that now express the receptor. This study provides the first definitive evidence for a physiological function of a neuropeptide receptor in molluscan animals.

neuroscience↗

bioRxiv2022

Single-cell transcriptome landscape of zebrafish liver reveals hepatocytes and immune cell interactions in understanding nonalcoholic fatty liver disease

Zebrafish have emerged as an attractive animal model for studying nonalcoholic fatty liver disease (NAFLD). However, little is known about the cell types and intercellular interactions in zebrafish liver. Here, we established a liver atlas that consists of 10 cell types using single-cell RNA sequencing. By examining the heterogeneity of hepatocytes and analyzing the expression of NAFLD-associated genes in the specific cluster, we provide a potential target cell model to study NAFLD. Additionally, our analysis identified two distinct resident macrophages with inflammatory and noninflammatory functions and characterized the successive stepwise development of T cell subtypes in the liver. Importantly, we uncovered possible molecular mechanisms and revealed the central regulation of macrophages on target cells of fatty liver by analyzing the cellular interaction between hepatocytes and immune cells. Our data provide valuable information for future research on NAFLD in zebrafish.

immunology↗

bioRxiv2021

Palmitoylation of PD-L1 Regulates Its Membrane Orientation and Immune Evasion

Recently identified palmitoylation of PD-L1 is essential for immune regulation. To elucidate the underlying molecular mechanism, we performed giant plasma membrane vesicle (GPMV) experiments, {micro}s-scale all-atom molecular dynamics (MD) simulations and immune killing experiments. GPMV experiments indicated that PD-L1 palmitoylation enhanced its lipid raft affinity. MD simulations revealed dramatically different membrane orientation states of PD-L1 in liquid-ordered (Lo, lipid raft) compared to liquid-disordered (Ld, non-raft) membrane environments. Ld region promoted the "lie-down" orientation of PD-L1, which could inhibit its association with the PD-1 protein on immune cells and thus promote the immune killing of cancer cells. This hypothesis was supported by immune killing experiments using{gamma}{delta} T cells as effector cells and NCI-H1299 lung cancer cells as target cells. In short, our study demonstrates that the palmitoylation affects PD-L1s membrane localization and then membrane orientation, which thus regulates its binding with T cell PD-1 and the immune regulation. These observations may guide therapeutic strategies by explicating the regulation of immune checkpoint proteins by post-translational modifications and membrane environments.

biophysics↗

bioRxiv2021

Clinically applicable rapid susceptibility testing of multi-drug resistant Staphylococcus aureus by mass spectrometry and extreme gradient boosting machine

Multi-drug resistant Staphylococcus aureus is one of the major causes of severe infections. Due to the delays of conventional antibiotic susceptibility test (AST), most cases were prescribed by experience with a lower recovery rate. Linking a 7-year study of over 20,000 Staphylococcus aureus infected patients, we incorporated mass spectrometry and machine learning technology to predict the susceptibilities of patients for 4 different antibiotics that can enable early antibiotic decisions. The predictive models were externally validated in an independent patient cohort, resulting in an area under the receiver operating characteristic curve of 0.94, 0.90, 0.86, 0.91 and an area under the precision-recall curve of 0.93, 0.87, 0.87, 0.81 for oxacillin (OXA), clindamycin (CLI), erythromycin (ERY) and trimethoprim-sulfamethoxazole (SXT), respectively. Moreover, our pipeline provides AST 24-36 h faster than standard workflows, reduction of inappropriate antibiotic usage with preclinical prediction, and demonstrates the potential of combining mass spectrometry with machine learning (ML) to assist early and accurate prescription. Therapies to individual patients could be tailored in the process of precision medicine.

bioinformatics↗

bioRxiv2021

Signatures of adaptive evolution during human to mink SARS CoV2 cross species transmission inform estimates of the COVID19 pandemic timing

One of the unique features of SARS-CoV-2 is that it mainly evolved neutrally or under purifying selection during the early pandemic. This contrasts with the preceding epidemics of the closely related SARS-CoV and MERS-CoV, both of which evolved adaptively. It is possible that the SARS-CoV-2 exhibits a unique or adaptive feature which deviates from other coronaviruses. Alternatively, the virus may have been cryptically circulating in humans for a sufficient time to have acquired adaptive changes for efficient transmission before the onset of the current pandemic. In order to test the above scenarios, we analyzed the SARS-CoV-2 sequences from minks (Neovision vision) and parenteral human strains. In the early phase of the mink epidemic (April to May 2020), nonsynonymous to synonymous mutation ratios per site within the spike protein was 2.93, indicating a selection process favoring adaptive amino acid changes. In addition, mutations within this protein concentrated within its receptor binding domain and receptor binding motif. Positive selection also left a trace on linked neutral variation. An excess of high frequency derived variants produced by genetic hitchhiking was found during middle (June to July 2020) and early late (August to September 2020) phases of the mink epidemic, but quickly diminished in October and November 2020. Strong positive selection found in SARS-CoV-2 from minks implies that the virus may be not unique in super-adapting to a wide range of new hosts. The mink study suggests that SARS-CoV-2 already went through adaptive evolution in humans, and likely been circulating in humans at least six months before the first case found in Wuhan, China. We also discuss circumstances under which the virus can be well-adapted to its host but fail to induce an outbreak.

evolutionary biology↗

bioRxiv2021

Microtubule assembly by soluble tau impairs vesicle endocytosis and excitatory neurotransmission via dynamin sequestration in Alzheimer's disease synapse model

Elevation of soluble wild-type (WT) tau occurs in synaptic compartments in Alzheimers disease. We addressed whether tau elevation affects synaptic transmission at the calyx of Held in brainstem slices. Whole-cell loading of WT human tau (h-tau) in presynaptic terminals at 10-20 {micro}M caused microtubule (MT) assembly and activity-dependent rundown of excitatory neurotransmission. Capacitance measurements revealed that the primary target of WT h-tau is vesicle endocytosis. Blocking MT assembly using nocodazole prevented tau-induced impairments of endocytosis and neurotransmission. Immunofluorescence imaging analyses revealed that MT assembly by WT h-tau loading was associated with an increased bound fraction of the endocytic protein dynamin. A synthetic dodecapeptide corresponding to dynamin-1-pleckstrin-homology domain inhibited MT-dynamin interaction and rescued tau-induced impairments of endocytosis and neurotransmission. We conclude that elevation of presynaptic WT tau induces de novo assembly of MTs, thereby sequestering free dynamins. As a result, endocytosis and subsequent vesicle replenishment are impaired, causing activity-dependent rundown of neurotransmission. Significance StatementWild-type human recombinant tau loaded in rodent presynaptic terminals inhibited vesicle endocytosis, thereby causing activity-dependent rundown of excitatory transmission. This endocytic block is caused by a sequestration of dynamin by excess microtubules newly assembled by tau and can be rescued by a peptide inhibiting the microtubules-dynamin interaction, or by the microtubule disassembler nocodazole. Thus, synaptic dysfunction can be induced by pathological increase of endogenous soluble tau in Alzheimer disease slice model.

neuroscience↗

bioRxiv2021

One viral sequence for each host? - The neglected within-host diversity as the main stage of SARS-CoV-2 evolution

The standard practice of presenting one viral sequence for each infected individual implicitly assumes low within-host genetic diversity. It places the emphasis on the viral evolution between, rather than within, hosts. To determine this diversity, we collect SARS-CoV-2 samples from the same patient multiple times. Our own data in conjunction with previous reports show that two viral samples collected from the same individual are often very different due to the substantial within-host diversity. Each sample captures only a small part of the total diversity that is transiently and locally released from infected cells. Hence, the global SARS-CoV-2 population is a meta-population consisting of the viruses in all the infected hosts, each of which harboring a genetically diverse sub-population. Advantageous mutations must be present first as the within-host diversity before they are revealed as between-host polymorphism. The early detection of such diversity in multiple hosts could be an alarm for potentially dangerous mutations. In conclusion, the main forces of viral evolution, i.e., mutation, drift, recombination and selection, all operate within hosts and should be studied accordingly. Several significant implications are discussed.

evolutionary biology↗