Biology subjects

Wan, L.

Publications and source records attributed to Wan, L..

At least 37 records · Page 2Linked to original sources

bioRxiv2025

A unified eIF1A+ luminal cells-centered hypoxic and "cold" tumor microenvironment promotes PCa progression among different subtypes

PCa is a malignancy with high heterogeneity arises from both tumor microenvironment (TME) and histological subtypes. To achieve superior clinical efficacy, it is imperative to identify unified progression drivers within such heterogeneity in PCa, thereby enabling the development of more consistent and effective therapeutic strategies. In this study, we applied imaging mass cytometry to stain 39 proteins on 71 tissues comprising para-cancer, low-grade acinar adenocarcinoma (LgPAC), high-grade PAC (HgPAC), intraductal carcinoma (IDC) and ductal adenocarcinoma (DAC) tissues, obtaining the spatial proteomic landscape of 345,233 single cells. We discovered a hypoxic eIF1A+ luminal epithelial (LE) cluster exhibiting both translational activation and immunosuppressive properties, which was enriched in high-risk PCa including HgPAC, IDC and DAC, and associated which tumor progression and unfavorable prognosis. Additionally, eIF1A+ LE orchestrates the formation of an immunologically "cold" TME, characterized by the low infiltration of anti-cancer immune cells including PD1- T cells CD163- macrophages. Through in vivo validation and investigator-initiated study, we further found that Homoharringtonine, an inhibitor targeting protein translation process, effectively inhibited PCa growth, alleviated hypoxic microenvironment, and enhanced immune cell infiltration. This study is the first to apply spatial proteomics to delineate consistent molecular features across histological subtypes, providing transformative insights for clinical management of PCa.

cancer biology↗

bioRxiv2025

Splice-switching ASOs targeting an Alu-derived exon in the AURKA 5'UTR collapse an SRSF1-AURKA-MYC oncogenic circuit in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) remains a highly lethal malignancy, driven by oncogenic KRAS mutations and dysregulated oncogenes, such as SRSF1, MYC, and AURKA. Although KRAS-targeted therapies are in development, resistance mechanisms underscore the need to identify alternative vulnerabilities. Here, we uncover an SRSF1-AURKA-MYC oncogenic circuit, wherein SRSF1 regulates AURKA 5UTR alternative splicing, enhancing AURKA protein expression; AURKA positively regulates SRSF1 and MYC post-translationally, independently of its kinase activity; and MYC in turn transcriptionally upregulates both SRSF1 and AURKA. Elevated SRSF1 in tumor cells promotes inclusion of an exonized Alu exon in the AURKA 5UTR, resulting in splicing-dependent mRNA accumulation and exon-junction- complex deposition. Modulating 5UTR splicing with splice-switching antisense oligonucleotides (ASOs) collapses the oncogenic circuit, reducing PDAC cell viability and triggering apoptosis. Our findings identify AURKA alternative splicing as a critical regulatory node and highlight ASO-mediated splice-switching as a potential therapeutic strategy that simultaneously targets SRSF1, AURKA, and MYC oncogenes.

cancer biology↗

bioRxiv2025

TIR immune signaling is blocked by phosphorylation to maintain plant growth

Toll/interleukin-1 receptor (TIR) domain proteins are immune signaling components and function as NAD+-cleaving enzymes to activate defense responses. Activation of TIRs represses growth and drives cell death in plants and promotes axon degeneration in animals, but how plant TIRs are repressed remains unclear. Here, we show that TIR NADase activity requires a conserved serine residue spatially close to the catalytic glutamate. The plant Ca2+-dependent protein kinases (CPKs), the mammalian Ca2+/calmodulin-dependent protein kinase II delta (CAMK2D) and TANK binding kinase 1 (TBK1) phosphorylate TIR domains at this conserved serine, which blocks TIR NADase activities and functions and thus maintains growth in plants and suppresses SARM1 TIR signaling in animals, respectively. Our findings define a fundamental molecular mechanism by which phosphorylation at a conserved serine residue blocks TIR signaling to balance growth and defense trade-offs.

plant biology↗

bioRxiv2025

The Arabidopsis TIRome informs the design of artificial TIR (Toll/interleukin-1 receptor) domain proteins

The TIR (Toll/interleukin-1 receptor) domain is an ancient protein module that functions in immune and cell death responses across the Tree of Life. TIR domains encoded by plants and prokaryotes function as enzymes to produce diverse small molecule immune signals. Plant genomes can encode hundreds of TIR-domain containing proteins - many of which confer important agricultural disease resistance as TIR-NLR (nucleotide-binding, leucine-rich repeat) immune receptors. Despite their importance, how natural variation influences TIR enzymatic output and immunity-associated cell death is largely unexplored. We assayed a complete collection of the TIR domains of Arabidopsis thaliana Col-0 (the "AtTIRome") to explore variation in TIR metabolite production and cell death signaling. Roughly half of the AtTIRome triggered cell death in transient assays. Artificial TIR proteins designed based on consensus sequences of the AtTIRomes cell death phenotypic classes revealed polymorphisms controlling variation in TIR cell death elicitation and metabolite production. Structure-function analyses of artificial TIRs revealed that natural variation in the "BB-loop", a flexible region overlying the catalytic pocket, determines differences in function across Arabidopsis TIR-containing proteins. We further demonstrate that artificial TIRs are functional on an NLR chassis and that BB-loop variation can tune the activity of a natural TIR-NLR protein. These findings shed light on the diversity of TIR outputs and reveal methods to design and engineer TIR-based immune receptors. Significance StatementTIR (Toll/interleukin-1 receptors) domain proteins perform immune signaling across the Tree of Life. TIR domains are enzymes that can process NAD+ to generate diverse small molecule signals. In order to better understand TIR-based signaling, we leveraged Arabidopsis natural variation across [~]150 TIR proteins to inform the design of artificial TIRs, define features that control output, and tune the output of a natural TIR immune receptor. The engineering of plant immune pathways will enable the optimization of disease resistance to safeguard yields.

plant biology↗

bioRxiv2025

scCausalVI disentangles single-cell perturbation responses with causality-aware generative model

Single-cell RNA sequencing provides detailed insights into cellular heterogeneity and responses to external stimuli. However, distinguishing inherent cellular variation from extrinsic effects induced by external stimuli remains a major analytical challenge. Here, we present scCausalVI, a causality-aware generative model designed to disentangle these sources of variation. scCausalVI decouples intrinsic cellular states from treatment effects through a deep structural causal network that explicitly models the causal mechanisms governing cell-state-specific responses to external perturbations while accounting for technical variations. Our model integrates structural causal modeling with cross-condition in silico prediction to infer gene expression profiles under hypothetical scenarios. Comprehensive benchmarking demonstrates that scCausalVI outperforms existing methods in disentangling causal relationships, quantifying treatment effects, generalizing to unseen cell types, and separating biological signals from technical variation in multi-source data integration. Applied to COVID-19 datasets, scCausalVI effectively identifies treatment-responsive populations and delineates molecular signatures of cellular susceptibility. Code availabilitySoftware is available at https://github.com/ShaokunAn/scCausalVI.

bioinformatics↗

bioRxiv2025

Integrate and generate single-cell proteomics from transcriptomics with cross-attention

MotivationSingle-cell RNA sequencing (scRNA-seq) and cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) have experienced rapid advancements in recent years, accompanied by the development of numerous methods for analyzing scRNA-seq and CITE-seq data. These innovations have enabled deeper insights into cellular heterogeneity and functional phenotypes. However, analyzing scRNA-seq and CITE-seq data within a unified framework remains a significant challenge in the field of single-cell analysis. Specifically, this challenge centers on two primary objectives: aligning scRNA-seq and CITE-seq cells within an integrated representation space and generating antibody-derived tag (ADT) measurements for scRNA-seq cells. ResultsBy incorporating interrelationships between cells into a deep generative model with cross-attention, we introduced scProca to integrate and generate single-cell proteomics from transcriptomics. scProca delivers state-of-the-art performance in both integration and generation tasks across benchmark datasets. Furthermore, scProca can accommodate cells across experimental batches, showcasing its flexibility in complex experimental contexts. AvailabilityThe code of scProca is available at https://github.com/xiongbiolab/scProca, and replication for this study is available at https://github.com/ZzzsHuqiaAao/scProca-reproducibility.

bioinformatics↗

bioRxiv2024

Engineered protein destabilization reverses intrinsic immune evasion for candidate vaccine pan-strain KSHV and SARS-CoV-2 antigens

Both Kaposi sarcoma herpesvirus LANA and SARS coronavirus 2 RdRp/nsp12 are highly conserved replication proteins that evade immune processing. By deleting the LANA central repeat 1 domain (LANA{Delta}CR1) or by dividing RdRp into two separated fragments (RdRpFrag) to maximize nascent protein mis-folding, cis peptide presentation was increased. Native LANA or RdRp SIINFEKL fusion proteins expressed in MC38 cancer cells were not recognized by activated OT-1 CD8+ cells against SIINFEKL but cytotoxic recognition was restored by expression of the corresponding modified proteins. Immunocompetent syngeneic mice injected with LANA- or RdRp-SIINFEKL MC38 cells developed rapidly-growing tumors with short median survival times. Mice injected with LANA{Delta}CR1- or RdRpFrag-SIINFEKL had partial tumor regression, slower tumor growth, longer median survival, as well as increased effector-specific tumor-infiltrating lymphocytes. These mice developed robust T cell responses lasting at least 90 days post-injection that recognized native viral protein epitopes. Engineered vaccine candidate antigens can unmask virus-specific CTL responses that are typically suppressed during native viral infection.

immunology↗

bioRxiv2024

Elevated NAD+ drives Sir2A-mediated GCβ deacetylation and OES localization for Plasmodium ookinete gliding and mosquito infection

cGMP signal-activated ookinete gliding is essential for mosquito midgut infection of Plasmodium in malaria transmission. During ookinete development, cGMP synthesizer GC{beta} polarizes to a unique localization <ookinete extrados site= (OES) until ookinete maturation and activates cGMP signaling for initiating parasite motility. However, the mechanism underlying GC{beta} translocation from cytosol to OES remains elusive. Here, we used protein proximity labeling to search the GC{beta}-interacting proteins in ookinetes of the rodent malaria parasite P. yoelii, and found the top hit Sir2A, a NAD+-dependent sirtuin family deacetylase. Sir2A interacts with GC{beta} throughout ookinete development. In mature ookinetes, Sir2A co-localizes with GC{beta} at OES in a mutually dependent manner. Parasites lacking Sir2A lose GC{beta} localization at OES, ookinete gliding, and mosquito infection, phenocopying GC{beta} deficiency. GC{beta} is acetylated at gametocytes but is deacetylated by Sir2A for OES localization at mature ookinetes. We further demonstrated that the level of NAD+, an essential co-substrate for sirtuin, increases during the ookinete development. The NAD+ at its maximal level until ookinete maturation promotes Sir2A-catalyzed GC{beta} deacetylation, ensuring GC{beta} localization at OES. This study highlights the spatiotemporal coordination of cytosolic NAD+ level and NAD+-dependent Sir2A in regulating GC{beta} deacetylation and dynamic localization for Plasmodium ookinete gliding.

microbiology↗

bioRxiv2024

A Library of Custom PEG-Lipids reveals a Double-PEG-Lipid with Drastically Enhanced Paclitaxel Solubility and Human Cancer Cell Cytotoxicity when used in Fluid Micellar Nanoparticles

Paclitaxel (PTX) is one of the most widely utilized chemotherapeutics globally. However, the extremely poor water solubility of paclitaxel necessitates a mechanism of delivery within blood. Fluid lipid PTX nanocarriers (lipids in the chain-melted state) show promise as PTX delivery vectors, but remain limited by their solubility of PTX within the membrane. To improve pharmacokinetics, membrane surfaces are typically coated with polyethylene glycol (PEG). Recent work has demonstrated the generation of a population of micelles within fluid lipid formulations containing a 2kDa PEG-lipid at a 10 mol% ratio. Driven by the positive curvature of the PEG-lipid (i.e. area of head group > area of tails), micelle-containing formulations were found to exhibit significantly higher uptake in cancer cells, cytotoxicity, and in vivo antitumor efficacy compared to formulations containing solely liposomes. Here, we describe the custom synthesis of a library of high-curvature micelle-inducing PEG-lipids and examine the effects of PEG chain length, chain branching (single- or double-PEG-lipid), and cationic charge on PTX solubility and cytotoxicity. We examined PEG-lipids at standard (10 mol%) and high (100-x mol%, where x=PTX mol%) formulation ratios. Remarkably, all formulations containing the synthesized high-curvature PEG-lipids had improved PTX solubility over unPEGylated formulations and commercially available DOPE-5k. The highest PTX solubility was found within the 100-xO_SCPLOWPTXC_SCPLOW mol% PEG-lipid micellar formulations, with particles made from 2k2 (two PEG2k chains) encapsulating 13 mol% PTX for up to 24 h. The pancreatic cancer cell line PC3 exhibited higher sensitivity to formulations containing PEG-lipid at 100-xO_SCPLOWPTXC_SCPLOW mol%, the most potent of which being formulations made from 2k2 (IC50 = 14 nM). The work presented here suggests formulations employing high-curvature PEG-lipids, particularly the double-PEG-lipid 2k2, hold great potential as next-generation PTX delivery systems owing to their high PTX solubility, enhanced cell cytotoxicity, and ability for precision targeting by affixation of ligands to the PEG molecules.

bioengineering↗

bioRxiv2024

An acidic loop in the FHA domain of the yeast meiosis-specific kinase Mek1 interacts with a specific motif in a subset of Mek1 substrates

The meiosis-specific kinase Mek1 regulates key steps in meiotic recombination in the budding yeast, Saccharomyces cerevisiae. MEK1 limits resection at the double strand break (DSB) ends and is required for preferential strand invasion into homologs, a process known as interhomolog bias. After strand invasion, MEK1 promotes phosphorylation of the synaptonemal complex protein Zip1 that is necessary for DSB repair mediated by a crossover specific pathway that enables chromosome synapsis. In addition, Mek1 phosphorylation of the meiosis-specific transcription factor, Ndt80, regulates the meiotic recombination checkpoint that prevents exit from pachytene when DSBs are present. Mek1 interacts with Ndt80 through a five amino acid sequence, RPSKR, located between the DNA binding and activation domains of Ndt80. AlphaFold Multimer modeling of a fragment of Ndt80 containing the RPSKR motif and full length Mek1 indicated that RPSKR binds to an acidic loop located in the Mek1 FHA domain, a non-canonical interaction with this motif. A second protein, the 5-3 helicase Rrm3, similarly interacts with Mek1 through an RPAKR motif and is an in vitro substrate of Mek1. Genetic analysis using various mutants in the MEK1 acidic loop validated the AlphaFold model, in that they specifically disrupt two-hybrid interactions with Ndt80 and Rrm3. Phenotypic analyses further showed that the acidic loop mutants are defective in the meiotic recombination checkpoint, and in certain circumstances exhibit more severe phenotypes compared to the NDT80 mutant with the RPSKR sequence deleted, suggesting that additional, as yet unknown, substrates of Mek1 also bind to Mek1 using an RPXKR motif. ARTICLE SUMMARYThe FHA domain is conserved module best known for creating protein complexes by binding to phosphorylated threonines on target proteins. This work identified a non-canonical mechanism by which the FHA domain of the yeast meiosis-specific kinase Mek1 interacts with two of its substrates, Ndt80 and Rrm3. An acidic loop within the FHA domain binds to RPXKR motifs in Ndt80 and Rrm3. Genetic evidence suggests that this FHA domain acidic loop is required binding to additional Mek1 substrates.

genetics↗

bioRxiv2024

Single-Cell multiomics reveals ENL mutation perturbs kidney developmental trajectory by rewiring gene regulatory landscape

Cell differentiation during organogenesis relies on precise epigenetic and transcriptional control. Disruptions to this regulation can result in developmental abnormalities and malignancies, yet the underlying mechanisms are not well understood. Wilms tumors, a type of embryonal tumor closely linked to disrupted organogenesis, harbor mutations in epigenetic regulators in 30-50% of cases. However, the role of these regulators in kidney development and pathogenesis remains unexplored. By integrating mouse modeling, histological characterizations, and single-cell transcriptomics and chromatin accessibility profiling, we show that a Wilms tumor-associated mutation in the chromatin reader protein ENL disrupts kidney development trajectory by rewiring the gene regulatory landscape. Specifically, the mutant ENL promotes the commitment of nephron progenitors while simultaneously restricting their differentiation by dysregulating key transcription factor regulons, particularly the HOX clusters. It also induces the emergence of abnormal progenitor cells that lose their chromatin identity associated with kidney specification. Furthermore, the mutant ENL might modulate stroma-nephron interactions via paracrine Wnt signaling. These multifaceted effects caused by the mutation result in severe developmental defects in the kidney and early postnatal mortality in mice. Notably, transient inhibition of the histone acetylation binding activity of mutant ENL with a small molecule displaces transcriptional condensates formed by mutant ENL from target genes, abolishes its gene activation function, and restores developmental defects in mice. This work provides new insights into how mutations in epigenetic regulators can alter the gene regulatory landscape to disrupt kidney developmental programs at single-cell resolution in vivo. It also offers a proof-of-concept for the use of epigenetics-targeted agents to rectify developmental defects.

cancer biology↗

bioRxiv2024

Force-Enhanced Sensitive Detection of New DNA-Interactive Agents from Microorganisms at the Single-Molecule Level

The discovery of microbial-derived DNA-interacting agents, which hold broad therapeutic potential, is inherently challenging due to the limited sensitivity and specificity of conventional methodologies. Our study introduces a pioneering application of single-molecule stretching assay (SMSA) in natural product chemistry to identify DNA-intercalating agents directly from microbial cultures or extracts. We demonstrate that mechanical force can enhance sensitivity by increasing both the binding affinity Ka and the quantity of ligands bound. The changes induced by intercalators in the counter length and overstretching transition of dsDNA yield a distinctive and highly specific signature indicative of DNA intercalative binding, thereby enabling straightforward detection of DNA intercalators even in trace amounts from microbial cultures. This methodology eliminates the need for extensive large-scale fermentation and purification processes, thus offering a more streamlined approach to DNA-intercalating natural product discovery. By applying SMSA to 17 microorganisms, we identified two DNA intercalator-producing strains: Streptomyces tanashiensis and Talaromyces funiculosus. Subsequently, three DNA intercalators, namely medermycin, kalafungin, and ligustrone B, were isolated and characterized. Among them, medermycin and kalafungin showed significant inhibitory effects against HCT-116 cancer cells, with IC50 values of 52 {+/-} 6 nM and 70 {+/-} 7 nM, respectively.

biophysics↗

bioRxiv2024

Graspot: A graph attention network for spatial transcriptomics data integration with optimal transport

Spatial transcriptomics (ST) technologies enable the measurement of mRNA expression while simultaneously capturing spot locations. By integrating ST data, the 3D structure of a tissue can be reconstructed, yielding a comprehensive understanding of the tissues intricacies. Nevertheless, a computational challenge persists: how to remove batch effects while preserving genuine biological structure variations across ST data. To address this, we introduce Graspot, a graph attention network designed for spatial transcriptomics data integration with unbalanced optimal transport. Graspot adeptly harnesses both gene expression and spatial information to align common structures across multiple ST datasets. It embeds multiple ST datasets into a unified latent space, facilitating the partial alignment of spots from different slices. Demonstrating superior performance compared to existing methods on four real spatial transcriptomics datasets, Graspot excels in ST data integration, including tasks that require partial alignment. In particular, Graspot unveils subtle tumor microenvironment structures of breast cancer, and accurately aligns the spatio-temporal transcriptomics data to reconstruct human heart developmental processes. The code for Graspot is available at https://github.com/zhan009/Graspot.

bioinformatics↗

bioRxiv2023

Action-outcome based flexible behavior requires medial prefrontal cortex lead and its enhanced functional connectivity with dorsomedial striatum

Cognitive flexibility plays a key role in ensuring an individuals survival, and its deficit is a key symptom in many mental conditions and neurodegenerative diseases. The prefrontal cortex and striatum are both essential to cognitive flexibility. However, how the prefrontal cortex and striatum communicate with each other to enable flexible decision-making is not well understood. Competing theories are raised, debating on which structure among these two leads the role in detecting and representing the new circumstances for a change, giving largely opposing predictions on neural activities in the prefrontal cortex and striatum during flexible behavior. To address this question, we trained head-restrained mice to perform an action-outcome based dynamic foraging task and simultaneously recorded single-neuron activities in the medial prefrontal cortex (mPFC) and dorsomedial striatum (DMS). In this task, the animal chooses one of two actions to obtain reward. The animal is guided only by previous reward outcomes. We report that mPFC but not DMS activity stores information about prior reward history. A large fraction of both mPFC and DMS neurons activity represents the difference in reward probability between two alternative options, namely the perceived reward probability difference (PRPD), a key decision variable that prescribes which subsequent choice to make. We find that mPFC neural activities track the change of PRPD earlier and faster than those in the DMS, and functional connectivity between mPFC and DMS increases with reducing overall reward proportion.

neuroscience↗

bioRxiv2023

The deubiquitinase USP9X regulates RIT1 protein abundance and oncogenic phenotypes

RIT1 is a rare and understudied oncogene in lung cancer. Despite structural similarity to other RAS GTPase proteins such as KRAS, oncogenic RIT1 activity does not appear to be tightly regulated by nucleotide exchange or hydrolysis. Instead, there is a growing understanding that the protein abundance of RIT1 is important for its regulation and function. We previously identified the deubiquitinase USP9X as a RIT1 dependency in RIT1-mutant cells. Here, we demonstrate that both wild-type and mutant forms of RIT1 are substrates of USP9X. Depletion of USP9X leads to decreased RIT1 protein stability and abundance and resensitizes cells to EGFR tyrosine kinase inhibitors. Our work expands upon the current understanding of RIT1 protein regulation and presents USP9X as a key regulator of RIT1-driven oncogenic phenotypes.

cancer biology↗

bioRxiv2023

RFC1 AAGGG pentanucleotide repeats form parallel G-quadruplex: structural implications for aberrant molecular cascades in CANVAS

A pentanucleotide repeat expansion (PRE) of (AAGGG)n in the replication factor C subunit 1 (RFC1) gene is recently identified as the genetic cause of cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS), and also linked to several other neurodegenerative disorders including the Parkinsons disease. However, the molecular mechanism by which RFC1 PRE drives pathology remains poorly understood. Here, for the first time we discovered and determined the high-resolution structures of parallel G-quadruplex formed by AAGGG repeats within the pathogenic RFC1 PRE, revealing an intriguing conformational plasticity at the 3-termi that allows stacking of multiple G4s. We further identify a molecular mechanism by which the DNA G4 in RFC1 PRE impedes polymerase processivity leading to replication stalling and transcription inhibition in vitro in a repeat-length-dependent manner, and the transcription inhibition could partially contribute to a reduced gene expression in cells. Our results demonstrate that the DNA G-quadruplex of RFC1 PRE participate in aberrant molecular cascades, and provide an unprecedented high-resolution structural target to discover helicases and ligands that resolve the pathogenic G4 for therapeutic intervention.

biochemistry↗

bioRxiv2023

Preclinical Screening of Splice-Switching Antisense Oligonucleotides in PDAC Organoids

Aberrant alternative splicing is emerging as a cancer hallmark and a potential therapeutic target. It is the result of dysregulated splicing factors or genetic alterations in splicing-regulatory cis-elements. Targeting individual altered splicing events associated with cancer-cell dependencies is a potential therapeutic strategy, but several technical limitations need to be addressed. Patient-derived organoids (PDOs) are a promising platform to recapitulate key aspects of disease states and to facilitate drug development for precision medicine. Here, we report an efficient antisense-oligonucleotide (ASO) transfection method to systematically evaluate and screen individual splicing events as therapeutic targets in pancreatic ductal adenocarcinoma (PDAC) organoids. This optimized delivery method allows fast and efficient screening of ASOs that reverse oncogenic alternative splicing. In combination with advancements in chemical modifications and ASO-delivery strategies, this method has the potential to accelerate the discovery of anti-tumor ASO drugs that target pathological alternative splicing.

pharmacology and toxicology↗

bioRxiv2023

Plasma membrane association and resistosome formation of plant helper immune receptors

Intracellular plant immune receptors, termed NLRs, respond to pathogen effectors delivered into plant cells. Activation of NLRs typically confers immunity. Sensor NLRs, involved in effector recognition, are either TIR-NLRs (TNLs) or CC-NLRs (CNLs). Helper NLRs, required for sensor NLR signaling, include CCR-NLRs (RNLs) and a special class of CNLs known as NRCs. Activated TNLs produce small molecules that induce an association between the EDS1/SAG101 heterodimer and the NRG1s helper RNLs. Auto active NRG1s oligomerize and form calcium signaling channels largely localized at the plasma membrane (PM). The molecular mechanisms of helper NLR PM association and effector induced NRG1 oligomerization are not well characterized. We find that both RNLs and NRCs require positively charged residues in the second and fourth helices of their CCR or CC domain for phospholipid binding and PM association before and after activation, despite conformational changes that accompany activation. We demonstrate that effector activation of TNLs induces NRG1 oligomerization at the PM and that the cytoplasmic pool of EDS1/SAG101 is critical for cell death function. EDS1/SAG101 cannot be detected in the oligomerized NRG1 resistosome, suggesting that additional unknown triggers might be required to induce the dissociation of EDS1/SAG101 from the previously described NRG1/EDS1/SAG101 heterotrimer before subsequent NRG1 oligomerization, or that the conformational changes resulting from NRG1 oligomerization abrogate the interface for EDS1/SAG101 association. Our data provide new observations regarding dynamic PM association during helper NLR activation and underpin an updated model for effector induced NRG1 resistosome formation.

plant biology↗