Biology subjects

Yang, J.

Publications and source records attributed to Yang, J..

At least 361 records · Page 20Linked to original sources

bioRxiv2024

High-throughput, multiplexed quantification, and sorting of single EVs at single-molecule level

We have developed a platform for the high-throughput, multiplexed, and ultra-sensitive profiling of individual extracellular vesicles (EVs) directly in plasma, which we call BDEVS - Agarose Bead-based Digital Single Molecule-Single EV Sorting. Unlike conventional approaches, BDEVS achieves single molecule sensitivity and moderate multiplexing (demonstrated 3-plex) without sacrificing the throughput (processing ten thousand of EVs per minute) necessary to resolve EVs directly in human plasma. Our platform integrates rolling circle amplification (RCA) of EV surface proteins, which are cleaved from single EVs, and amplified within agarose droplets, followed by flow cytometry-based readout and sorting, overcoming steric hindrance, non-specific binding, and the lack of quantitation of multiple proteins on EVs that have plagued earlier approaches. We evaluated the analytical capabilities of BDEVS through head-to-head comparison with gold-standard technologies, and demonstrated a [~]100x improvement in the limit of detection of EV subpopulations. We demonstrate the high throughput ([~]100k beads / minute) profiling of individual EVs for key immune markers PD-L1, CD155, and the melanoma tumor marker TYRP-1, and showed that BDEVS can precisely quantify and sort EVs, offering unprecedented resolution for analyzing tumor-immune interactions and detecting rare EV subpopulations in complex clinical specimens. We demonstrate BDEVSs potential as a transformative tool for EV-based diagnostics and therapeutic monitoring in the context of cancer immunology by analyzing plasma samples from patients with melanoma, where EV heterogeneity plays a critical role in disease progression and response to therapy. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=93 SRC="FIGDIR/small/621423v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@1a8a542org.highwire.dtl.DTLVardef@f9b9f0org.highwire.dtl.DTLVardef@11e4758org.highwire.dtl.DTLVardef@de1645_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2024

Synthesis of USC-093 and comparison with its promoiety enantiomer USC-093D against adenovirus in vitro and in a Syrian hamster model

Adenovirus infections of immunocompromised humans are a significant source of morbidity and mortality. At present, no drug has been approved by FDA for the treatment of adenovirus infections. A current treatment of such infections is off-label use of an antiviral acyclic nucleotide phosphonate, cidofovir (CDV, (S)-HPMPC), which requires i.v. administration and has dose-limiting kidney toxicity. We recently reported that USC-093, a homoserinamide analogue of the tyrosinamide (S)- HPMPA prodrug USC-087, was orally effective at a 10 mg/kg against disseminated human adenovirus infection (HAdV-C6) in a Syrian hamster model, although their efficacy was marginal after respiratory infection. Neither prodrug manifested GI toxicity. Unlike USC-087, USC-093 showed no significant nephrotoxicity at the effective dose. Here, we describe in detail the synthesis of USC-093 and also its D-homoserinamide analogue, USC-093D, in four steps (20-40% overall yield) starting from Boc-protected L-homoserine or D-homoserine lactone, respectively. The two stereoisomeric prodrugs had EC50 30-70 nM vs. Ad5 or 1-6 nM vs. Ad6 in HFF cells, with USC-093D giving the lower values. The prodrugs were 30-59x more potent vs. Ad5 and 82-332x more potent than Ad6 relative to the positive control, CDV. To ascertain whether D-chirality in the promoiety could enhance the performance of the prodrug in vivo, USC-093D and USC-093 were compared in the Syrian hamster model (treated from day 1 q.d at an experimentally determined maximum tolerated oral dose of 20 mg/kg)). In this study, the hamsters were instilled i.n. with vehicle or 4X1010 PFU/kg of HAdV-C6 to promote lung infection. Oral valganciclovir (VGCV) at 200 mg/kg b.i.d. was used as the positive control. The body weights were recorded daily, and at 3 days post challenge, gross pathological observation was performed. Lung samples were collected, and the virus burden was determined by TCID50 assay. The results show that altering homoserine stereochemistry did not markedly improve the efficacy of the orally administered prodrug, consistent with the premise that its mechanism of transport is likely not dependent on stereoselective pathways, such as hPEPT1-mediated uptake.

biochemistry↗

bioRxiv2024

Comparative spatiotemporal single cell transcriptomes reveal rewiring of pre-existing regulations during emergence of Kranz anatomy in C4 grasses

Many of the worlds most productive food and bioenergy crops use C4 photosynthesis, which have high photosynthetic efficiency due to a Kranz anatomy-based CO2 concentrating mechanism. Here, we took a comparative transcriptomics approach using single cell spatial transcriptomes of leaf primordia for maize (Zea mays) and single cell RNA-seq (scRNA-seq) atlases of corresponding leaf tissues for three C4 species (Zea mays, Sorghum bicolor, Setaria viridis) and one C3 rice (Oryza sativa) to study regulatory networks involved in the development and evolution of Kranz anatomy. We show that the formation of Kranz anatomy involves extensive recruitment and modification of pre-existing regulatory modules, especially the SHR-SCR module and the auxin signaling pathway. Members of the INDETERMINATE DOMAIN (IDD) family transcription factors, including IDD7 and IDDP1, contribute to the modification of the involved modules. These extensive recruitment and modification of existing genetic regulatory programs underlie the repeated emergence of C4 photosynthesis during evolution.

plant biology↗

bioRxiv2024

Stratified analysis identifies HIF-2α as a therapeutic target for highly immune-infiltrated melanomas

While immune-checkpoint blockade (ICB) has revolutionized treatment of metastatic melanoma over the last decade, the identification of broadly applicable robust biomarkers has been challenging, driven in large part by the heterogeneity of ICB regimens and patient and tumor characteristics. To disentangle these features, we performed a standardized meta-analysis of eight cohorts of patients treated with anti-PD-1 (n=290), anti-CTLA-4 (n=175), and combination anti-PD-1/anti-CTLA-4 (n=51) with RNA sequencing of pre-treatment tumor and clinical annotations. Stratifying by immune-high vs -low tumors, we found that surprisingly, high immune infiltrate was a biomarker for response to combination ICB, but not anti-PD-1 alone. Additionally, hypoxia-related signatures were associated with non-response to anti-PD-1, but only amongst immune infiltrate-high melanomas. In a cohort of scRNA-seq of patients with metastatic melanoma, hypoxia also correlated with immunosuppression and changes in tumor-stromal communication in the tumor microenvironment (TME). Clinically actionable targets of hypoxia signaling were also uniquely expressed across different cell types. We focused on one such target, HIF-2, which was specifically upregulated in endothelial cells and fibroblasts but not in immune cells or tumor cells. HIF-2 inhibition, in combination with anti-PD-1, enhanced tumor growth control in pre-clinical models, but only in a more immune-infiltrated melanoma model. Our work demonstrates how careful stratification by clinical and molecular characteristics can be leveraged to derive meaningful biological insights and lead to the rational discovery of novel clinical targets for combination therapy.

cancer biology↗

bioRxiv2024

Decoding the Functional Interactome of Non-Model Organisms with PHILHARMONIC

Despite the widespread availability of genome sequencing pipelines, many genes remain part of the genome's "dark matter," where existing inference tools cannot even begin to guess the biological function of their proteins from sequence alone. This challenge is especially pronounced in organisms that are highly evolutionarily distant from well-studied models, where homology-based methods break down. Here, we describe PHILHARMONIC, a computational method that combines deep learning-based de novo protein interaction network inference with robust unsupervised spectral clustering and remote homology to illuminate functional organization in any non-model organism. From only a sequenced proteome, we show PHILHARMONIC generates meaningful functional hypothesis for protein functions, functional communities, and higher-order network structure. We validate its performance using experimental gene expression and pathway data in D. melanogaster, and we demonstrate its broad utility by analyzing temperature sensing and stress response pathways in the reef-building coral P. damicornis and its algal symbiont C. goreaui. PHILHARMONIC provides a general-purpose engine for functional discovery and biological hypothesis generation in non-model organisms, enabling systems-level insights across the full diversity of life.

bioinformatics↗

bioRxiv2024

The aberrant language network dynamics in autism ages 5-40 years

Language impairments across both structural components and pragmatic use are frequently observed in individuals with autism spectrum disorder (ASD). These difficulties are thought to stem from atypical brain development and abnormal network interactions, yet an integrative network-level model accounting for such impairments remains lacking. To bridge this gap, we applied the dynamic meta-networking framework of language, a theoretical model capturing domain-segregation dynamics during rest, to examine age-related changes (5-60 years) in cortical language networks in individuals with ASD. To further probe the biological underpinnings of these dynamics, we quantified spatial correspondences between network state hubs and gene co-expression modules as well as neurotransmitter receptor distributions. We identified distinct language meta-states characterized by domain-segregation connectivity patterns, which exhibited spatial alignment with gene co-expression modules and neurotransmitter systems. Individuals with ASD showed state-dependent developmental trajectories marked by age-related hypo- and hyper-connectivity. Critically, these network alterations strongly predicted verbal IQ and communicative difficulties, but were unrelated to social functioning or stereotyped behaviors. Our findings provide novel evidence that language-related network dynamics in ASD are developmentally altered, biologically grounded, and selectively linked to verbal and communicative impairments. These results advance a network-level model of language dysfunction in ASD and highlight potential mechanistic pathways for targeted interventions. Lay SummaryLanguage challenges are common in autism and can affect both learning language and using it in everyday conversations. In people aged 5-60, we found distinct, age-changing patterns in how the brains language areas connect at rest; these patterns align with basic biology (genes and brain chemicals) and strongly relate to verbal ability and daily communication, but not to social difficulties or repetitive behaviors. These results suggest clear, brain-based targets for earlier and more tailored support for language problems in autism.

neuroscience↗

bioRxiv2024

Unraveling transposable element-mediated regulatory landscape in diverse human immune cells

Transposable elements (TEs) are key contributors to genetic novelty. Despite increasing evidence of their importance, their roles in shaping the regulatory landscape of diverse immune cell populations remain largely unclear. Using single-cell multiome data from human peripheral blood mononuclear cells, we annotated the cell-specific cis-regulatory elements for major immune cell populations and identified a highly cell-specific signature of the overrepresented TE families. Focusing on monocytes that bear fast-evolving transcriptomes, we found that high proportions of their enhancers are TE-derived and bound by multiple pioneer transcription factors. Among them, we confirmed that the core myeloid regulator SPI1 can bind and regulate hundreds of TE-derived enhancers, which further affect the expression of adjacent immune genes. Additionally, interspecies comparison reveals that non-conserved monocyte enhancers are frequently generated by lineage-specific TE insertions, and correlate with the evolved gene expression between human and mouse. Overall, our study supports the importance of TEs in shaping the regulatory landscape of diverse immune cell populations.

genomics↗

bioRxiv2024

CADET: Enhanced transcriptome-wide association analyses in admixed samples using eQTL summary data

A transcriptome-wide association study (TWAS) is a popular statistical method for identifying genes whose genetically-regulated expression (GReX) component is associated with a trait of interest. Most TWAS approaches fundamentally assume that the training dataset (used to fit the gene expression prediction model) and testing GWAS dataset are from the same ancestrally homogenous population. If this assumption is violated, studies have shown a marked negative impact on expression prediction accuracy as well as reduced power of the downstream genetrait association test. These issues pose a particular problem for admixed individuals, whose genomes represent a mosaic of multiple continental ancestral segments. To resolve these issues, we present CADET, which enables powerful TWAS of admixed cohorts leveraging the local-ancestry (LA) information of the cohort along with summary-level eQTL data from reference panels of different ancestral groups. CADET combines multiple polygenic risk score models based on the summary-level eQTL reference data to predict LA-aware GReX components in admixed test samples. Using simulated data, we compare the imputation accuracy, power, and type I error rate of our proposed LA-aware approach to LA-unaware methods for performing TWASs. We show that CADET performs optimally in nearly all settings regardless of whether the genetic architecture of gene expression is dependent or independent of ancestry. We further illustrate CADET by performing a TWAS of 29 common blood biochemistry phenotypes within an admixed cohort from the UK Biobank and identify 18 hits unique to our LA-aware strategy with the majority of hits supported by existing GWAS findings.

genetics↗

bioRxiv2024

α-Synuclein Strain Dynamics Correlate with Cognitive Shifts in Parkinson's Disease

-Synuclein (-syn) strains can serve as discriminators between Parkinsons disease (PD) and related -synucleinopathies. The relationship between -syn strain dynamics and clinical performance as patients transition from normal cognition (NC) to cognitive impairment (CI) is not known. Here, we show that the biophysical properties and neurotoxicity of -syn strains change as PD cognitive status transitions from NC to mild cognitive impairment (PD-MCI) and dementia (PD-D). Both cross-sectional and longitudinal analyses reveal distinct -syn strains in PD patients correlating to their level of cognitive impairment. Machine learning (ML) was employed to achieve high classification accuracy. The combination of thioflavin T (ThT) maximal fluorescence intensity (mfi), max slope of rise curve (forming rate), lag time (tlag), 20% time (t20), and half-time (t50), dynamic light scattering (DLS) (peak number, [1/2] peak size, [1/2] peak intensity) and neurotoxicity together with demographic variables for model training yielded superior performance (89[~]99% accuracy in the 4- and 2- classification schema) compared to individual features alone in classifying cognitive status. For the longitudinal study, DLS peak number emerged as the strongest predictor of cognitive transition (HR = 0.12, P = 0.002), with the optimal predictive model combining DLS peak number, sex, education, DLS peak 1 size, and DLS peak 2 polydispersity achieving high accuracy (C-index of [~]93%). This study presents evidence that individuals with PD have different -syn strains correlating to their cognitive status and highlights the potential of -syn strain dynamics to guide future diagnosis, management, and stratification of PD patients. One Sentence SummaryDistinct features of -syn strains change with cognitive decline in Parkinsons disease and AI-based analysis incorporating these combined characteristics serves as a powerful tool for PD clinical stratification.

neuroscience↗

bioRxiv2024

Evaluation of Machine Learning-Assisted Directed Evolution Across Diverse Combinatorial Landscapes

Various machine learning-assisted directed evolution (MLDE) strategies have been shown to identify high-fitness protein variants more efficiently than typical wet-lab directed evolution approaches. However, limited understanding of the factors influencing MLDE performance across diverse proteins has hindered optimal strategy selection for wet-lab campaigns. To address this, we systematically analyzed multiple MLDE strategies, including active learning and focused training using six distinct zero-shot predictors, across 16 diverse protein fitness landscapes. By quantifying landscape navigability with six attributes, we found that MLDE offers a greater advantage on landscapes which are more challenging for directed evolution, especially when focused training is combined with active learning. Despite varying levels of advantage across landscapes, focused training with zero-shot predictors leveraging distinct evolutionary, structural, and stability knowledge sources consistently outperforms random sampling for both binding interactions and enzyme activities. Our findings provide practical guidelines for selecting MLDE strategies for protein engineering.

bioengineering↗

bioRxiv2024

Unbiased mapping of cereblon neosubstrate landscape by high-throughput proteomics

Molecular glue degraders (MGDs) are small molecules that harness the ubiquitin-proteasome system to induce degradation of target proteins, including those lacking conventional druggable pockets. Given the challenges in their rational design, MGD discovery predominantly relies on screening-based approaches, such as cell viability assays. However, one potential limitation of such screening methods is the risk of overlooking non-essential neosubstrates of potential therapeutic value. To address this concern, we present a high-throughput proteome-wide MGD screening platform utilizing label-free, data-independent acquisition mass spectrometry (DIA-MS) for integrated proteomics and ubiquitinomics analysis. Processing a diverse set of 100 CRBN-ligands across two cancer cell lines reveals a broad array of neosubstrates, including 50 novel candidates validated by MS-based ubiquitinomics. These findings considerably expand the current landscape of CRBN-mediated neosubstrates. Comprehensive hit validation and structure-degradation relationship analyses guided by global proteomics, identifies highly selective and potent phenyl glutarimide-based degraders of novel neosubstrates, including KDM4B, G3BP2 and VCL, none of which contain the classical CRBN degron motif. This study demonstrates that comprehensive, high-throughput proteomic screening offers new opportunities in MGD drug discovery.

biochemistry↗

bioRxiv2024

DDX41 dissolves G-quadruplexes to maintain erythroid genome integrity and prevent cGAS-mediated cell death

Deleterious germline DDX41 variants constitute the most common inherited predisposition disorder linked to myeloid neoplasms (MNs). The role of DDX41 in hematopoiesis and how its germline and somatic mutations contribute to MNs remain unclear. Here we show that DDX41 is essential for erythropoiesis but dispensable for the development of other hematopoietic lineages. Using stage-specific Cre models for erythropoiesis, we reveal that Ddx41 knockout in early erythropoiesis is embryonically lethal, while knockout in late-stage terminal erythropoiesis allows mice to survive with normal blood counts. DDX41 deficiency induces a significant upregulation of G-quadruplexes (G4), noncanonical DNA structures that tend to accumulate in the early stages of erythroid precursors. We show that DDX41 co-localizes with G4 on the erythroid genome. DDX41 directly binds to and dissolves G4, which is significantly compromised in MN-associated DDX41 mutants. Accumulation of G4 by DDX41 deficiency induces erythroid genome instability, defects in ribosomal biogenesis, and upregulation of p53. However, p53 deficiency does not rescue the embryonic death of Ddx41 hematopoietic-specific knockout mice. In parallel, genome instability also activates the cGas-Sting pathway, which is detrimental to survival since cGas-deficient and hematopoietic-specific Ddx41 knockout mice are viable without detectable hematologic phenotypes, although these mice continue to show erythroid ribosomal defects and upregulation of p53. These findings are further supported by data from a DDX41 mutated MN patient and human iPSC-derived bone marrow organoids. Our study establishes DDX41 as a G4 dissolver, essential for erythroid genome stability and suppressing the cGAS-STING pathway.

cancer biology↗

bioRxiv2024

Multi-modal profiling identifies CD4+CXCR5+PD-1- Tfh cells as prognostic and predictive biomarkers for response to R-CHOP therapy in human DLBCL

Despite the improvements in clinical outcomes for patients with Diffuse Large B-Cell Lymphoma (DLBCL), a significant proportion of those patients still face challenges with refractory/relapsed (R/R) disease after receiving first-line R-CHOP treatment. Characterizing the heterogeneity of the tumor microenvironment (TME) in diffuse large B cell lymphoma (DLBCL) is crucial for understanding relapsed/refractory disease. However, the complex and diverse nature of the TME has impeded progress. Here, using single-cell RNA sequencing(scRNA-seq), we explored the DLBCL landscape at single-cell resolution, profiling 77,344 cells from both primary and relapsed DLBCL patients. We further investigated the shared and distinct molecular and cellular features of tumor microenvironment in both primary and relapsed DLBCL tumors by integrating next-generation DNA sequencing data and multiple scRNA-seq datasets from total 72,351 cells. Our results demonstrated that there was a significant decrease of CD4+CXCR5+PD-1- Tfh cells, along with excessive activation of the TNF-NF{kappa}B signaling pathways in malignant B cells in R/R disease. Furthermore, by using multiplex IHC, we confirmed that CD4+CXCR5+PD-1- Tfh cells are prognostic and predictive biomarkers for response to R-CHOP treatment. As a proof of concept, we successfully generated mutilplexed images of CD4+CXCR5+PD-1- Tfh cells from a single DAPI staining in human DLBCL tissues through using generative artificial intelligence. Our study offers critical insights into the heterogeneity and molecular features of DLBCL, shedding light on the crucial role of CD4+CXCR5+PD-1- Tfh cells in the recurrent process. HighlightsO_LIShared and distinct molecular and cellular features of tumor microenvironment in both primary and relapsed DLBCL tumors; C_LIO_LIThe characteristic of relapsed DLBCL TME is a dysfunctional immune microenvironment with a significant decrease of CD4+CXCR5+PD-1- Tfh cells. C_LIO_LICD4+CXCR5+PD-1- Tfh cells are prognostic and predictive biomarkers for response to R-CHOP treatment C_LIO_LIDetermination of CD4+CXCR5+PD-1- Tfh cells in human DLBCL tissues through using generative artificial intelligence. C_LI

immunology↗

bioRxiv2024

Estrogen Receptor 1 Signaling in Hepatic Stellate Cells Designates Resistance to Liver Fibrosis

The prevalence and severity of liver fibrosis appear higher in men than in premenopausal women, while postmenopausal women exhibit the worsened disease. However, the pathophysiological mechanism underlying such clinical observations remains incompletely understood. Here, we show that sex hormone depletion in adult female mice exaggerates the model of liver fibrosis, while estradiol replacement in castrated male mice is sufficient to mitigate the disease severity. Transcriptomic analyses and immunohistochemistry then demonstrate that both human and mouse hepatic stellate cells (HSCs), the primary cell type responsible for extracellular fibrous depositions, predominantly express the estrogen receptor 1 (ESR1). Of importance, genetic deletion of ESR1 in mouse HSCs markedly promotes liver fibrosis. Moreover, chromatin immunoprecipitation followed by sequencing (ChIP-seq) and in vitro manipulations reveal that ESR1 can directly target the expression of fibrosis-related genes in HSCs. Together, this study has elucidated a critical aspect of ESR1 signaling in the sexual dimorphism of liver fibrosis.

pathology↗

bioRxiv2024

Liver CYP4A autophagic-lysosomal degradation (ALD): A major role for the autophagic receptor SQSTM1/p62 through an uncommon target interaction site

The hepatic P450 hemoproteins CYPs 4A are typical N-terminally anchored Type I endoplasmic reticulum (ER)-proteins, that are inducible by hypolipidemic drugs and other "peroxisome proliferators". They are engaged in the {omega}-/{omega}-1-oxidation of various fatty acids including arachidonic acid, prostaglandins and leukotrienes and in the biotransformation of some therapeutic drugs. Herein we report that of the mammalian liver CYPs 4A, human CYP4A11 and mouse Cyp4a12a are preferential targets of the ER-lysosome-associated degradation (ERLAD). Consequently, these proteins are stabilized both as 1%Triton X100-soluble and -insoluble species in mouse hepatocytes and HepG2-cells deficient in the autophagic initiation ATG5-gene. Although these proteins exhibit surface LC3-interacting regions (LIRs) that would target them directly to the autophagosome, they nevertheless interact intimately with the autophagic receptor SQSTM1/p62. Through structural deletion analyses and site-directed mutagenesis, we have identified the Cyp4A-interacting p62 subdomain to lie between residues 170 and 233, which include its Traf6-binding and LIM-binding subdomains. Mice carrying a liver-specific genetic deletion of p62 residues 69-251 (p62Mut) that includes the CYP4A-interacting subdomain also exhibit Cyp4a-protein stabilization both as Triton X100-soluble and -insoluble species. Consistently, p62Mut mouse liver microsomes exhibit enhanced {omega}- and {omega}-1-hydroxylation of arachidonic acid to its physiologically active metabolites 19- and 20-HETEs relative to the corresponding wild-type mouse liver microsomes. Collectively, our findings suggest that any disruption of CYP4A ERLAD results in functionally active P450 protein and consequent production of proinflammatory metabolites on one hand, and insoluble aggregates on the other, which may contribute to pathological aggregates i.e. Mallory-Denk bodies/inclusions, hallmarks of many liver diseases.

cell biology↗

bioRxiv2024

Engineered Age-Mimetic Breast Cancer Models Reveal Differential Drug Responses in Young and Aged Microenvironments

Aging is one of the most significant risk factors for breast cancer. With the growing interests in the alterations of the aging breast tissue microenvironment, it has been identified that aging is related to tumorigenesis, invasion, and drug resistance. However, current pre-clinical disease models often neglect the impact of aging and sometimes result in worse clinical outcomes. In this study, we utilized aged animal-generated materials to create and validate a novel age-mimetic breast cancer model that generates an aging microenvironment for cells and alters cells towards a phenotype found in the aged environment. Furthermore, we utilized the age-mimetic models for 3D breast cancer invasion assessment and high-throughput screening of over 700 drugs in the FDA-approved drug library. We identified 36 potential effective drug targets and 34 potential drug targets with different drug responses in different age groups, demonstrating the potential of this age-mimetic breast cancer model for further in-depth breast cancer studies and drug development.

bioengineering↗

bioRxiv2024

Environmental polysulfides promote protein disulfide bond formation of microorganisms growing under anaerobic condition

Polysulfides are rich in anaerobic and microbial metabolism active environments. Anaerobic survival of microorganisms requires the formation of protein disulfide bond (DSB). The relation between environmental polysulfides and anaerobic DSB formation has not been studied so far. Herein, we discovered that environmental polysulfides can efficiently mediate protein DSB formation of microorganisms under anaerobic condition. We used polysulfides to treat proteins including roGFP2, Trx1, and DsbA under anaerobic condition and found that all three proteins formed intramolecular DSB in vitro. The growth of E. coli {Delta}dsbB was reduced and the amount of its intracellular protein DSB was decreased under anaerobic condition. However, treating the mutant strain with polysulfides recovered the growth and reversed DSB decrease. Treating E. coli {Delta}dsbA with polysulfides promoted DSB formation of its periplasmic roGFP2 and recovered its growth under anaerobic condition. In addition, treating Schizosaccharomyces pombe with polysulfides led to increase of the intracellular protein DSB content. Thus, our study reveals that environmental polysulfides can promote DSB formation independent of the enzymatic DSB mediating system and oxygen. In this aspect, environmental polysulfides are beneficial for the survival of microorganisms in anaerobic habitats. IMPORTANCEHow polysulfides benefit adaption of microorganisms to anaerobic environments are unclear. Our study reveals that environmental polysulfides efficiently facilitate protein DSB formation under anaerobic condition. Polysulfides contain zero valent sulfur atoms (S0), which can be transferred to the thiol group of cysteine residue. This S0 atom gets two electrons from two cysteine residues and becomes reduced H2S, leaving two cysteine residues in disulfide bond form. Anaerobic growth of microorganisms was benefited from the formation of DSB. This finding paves the way for a deeper understanding of the intricate relationship between polysulfides and microorganisms in environmental contexts.

molecular biology↗

bioRxiv2024

Endosomal hyper-acidification via proton-activated chloride channel deletion in neurons impairs AMPA receptor endocytosis and LTD

Endosomal homeostasis is critical for neuronal function, including the post-synaptic trafficking of -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs). Dynamic AMPAR trafficking is a major component of synaptic plasticity, such as hippocampal long-term potentiation (LTP) and long-term depression (LTD) and is thought to be required for learning and memory. Dramatic alteration of endosomal pH has been reported to negatively affect synaptic transmission and neural development, but the underlying mechanisms by which pH is involved in AMPAR trafficking are unclear. Here, we show that the proton-activated chloride (PAC) channel localizes to early and recycling endosomes along neuronal dendrites and prevents hyper-acidification of endosomes. To directly measure AMPAR endocytosis, we used a new method to assess LTD using HaloTag-GluA2 and found that the loss of PAC reduces AMPAR internalization during chemical LTD in primary neurons, while AMPAR trafficking in unstimulated cells or during chemical LTP is unaffected. Consistently, pyramidal neuron-specific PAC knockout mice had impaired hippocampal LTD, but not LTP, and performed poorly in the Morris water maze reversal test, exhibiting an inability to adapt to changing environments (also referred to as behavioral flexibility). We conclude that proper maintenance of pH by PAC is important during LTD to regulate AMPAR trafficking in a manner critical for animal physiology and behavior. SummaryThe ability to adapt to changing environments stems from the plasticity of neurons, which can modulate their synaptic strength in response to neural activity. We discovered a novel mechanism by which an endosomal proton-activated chloride channel (PAC) is involved in synaptic weakening, or long-term depression (LTD). To improve tools used to study LTD, we developed a live-cell imaging assay to directly observe -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) endocytosis. PAC-deficient neurons have hyper-acidified endosomes and fail to endocytose AMPARs during LTD. Neuron-specific PAC knockout mice have impaired hippocampal LTD and fail to adapt to changes in their environment. The role of endosomal pH in synaptic function is understudied, and our results provide a novel mechanism whereby PAC can affect synaptic LTD.

neuroscience↗