Biology subjects

Wong, C. J.

Publications and source records attributed to Wong, C. J..

16 recordsLinked to original sources

bioRxiv2026

TurboID proximity labeling reveals protein interaction networks for germline Argonautes

In the germline, small RNA-mediated gene regulatory pathways are associated with phase separated condensates known as germ granules across species. Germ granules can be challenging to purify based on their biophysical properties, therefore we used an in vivo proximity labeling approach, TurboID, to define the proximal interaction networks of the germ granule-localized Argonaute proteins: CSR-1, PRG-1/Piwi, PPW-2/WAGO-3, WAGO-1 and WAGO-4, and the nuclear-enriched Argonaute HRDE-1 as a comparator, in C. elegans. We found that although CSR-1 and WAGO-4 bind to the same set of 22G- small RNAs and target an overlapping set of germline genes, they possess distinct proximal interaction networks. Displacement of WAGO-4 from the germ granules highlights distinct interactors involved in chromosome biology and points to a potential nuclear role for WAGO-4. PRG-1/Piwi, WAGO-1, and PPW-2/WAGO-3, act in a common pathway and share an interaction network, while HRDE-1 displays a distinct interaction network that highlights its potential to influence splicing, rather than its widely accepted role in histone modification. Performing TurboID on other sRNA pathway factors, including the RdRP RRF-1 led us to uncover a potential nuclear role for this protein, and overlapping our TurboID data with published proximity labeling data enabled us to identify a core set of eleven mostly uncharacterized proteins that play roles in fertility, germ granule organization, and transgenerational epigenetic inheritance. One of these factors, D2005.4, appears to be a heme-binding germ granule-localized protein with a Tetratricopeptide Repeat Domain that interacts with all germ granule AGOs and may play scaffolding or enzymatic roles in germ granules. Collectively, our work highlights the utility of proximity labelling to uncover insights into AGO and sRNA pathway factor function and identify new factors that could be of importance in germ cell biology.

developmental biology↗

bioRxiv2026

PRMT1 arginine methylation of MCM4 restricts ssDNA gap formation during DNA replication

Replication-associated single-stranded DNA (ssDNA) gaps are increasingly recognized as major sources of genome instability, but how replisome-associated mechanisms suppress their formation remains unclear. Here we identify protein arginine methyltransferase 1 (PRMT1) as a replisome-associated methyltransferase that promotes DNA synthesis and fork integrity. PRMT1 localizes to active forks and its depletion or inhibition slows fork progression in multiple human cell types. We identify MCM4 as a direct PRMT1 substrate and show that methylation-deficient MCM4 causes spontaneous replication stress, elevated RPA, and nuclease-sensitive nascent DNA tracts, indicating persistent daughter-strand gaps. Despite these defects, methylation-deficient MCM4 cells exhibit apparent fork acceleration, consistent with discontinuous DNA synthesis. By contrast, PRMT1 depletion slows forks and selectively reduces fork association of SMC5/6 without broadly disrupting core replisome components. Together, these data support a model in which PRMT1-dependent methylation of MCM4 suppresses gap-prone DNA synthesis, while fork-associated SMC5/6 stabilizes vulnerable gap-containing intermediates.

molecular biology↗

bioRxiv2025

H3.3 De Novo Mutations Alter Lysine 36 Methylation via Distinct Mechanisms

Bryant-Li-Bhoj syndrome (BLBS) is caused by de novo mutations on histone H3.3 and is generally characterized by severe neurodevelopmental deficits. Oncogenic H3.3 amino acid substitutions were described over the past decade, but the molecular impact of BLBS mutations remained unstudied. The remarkable number and spread of the missense mutations led us to hypothesize that some converge on the same downstream effectors. We recently showed that H3.3G34R/V substitutions, seen in both cancer and BLBS, impair associations with the DNMT3A DNA methyltransferase. Our proteomic, enzymatic, and structural analyses now show that H3.3 BLBS mutations flanking glycine 34 have surprisingly stark effects on H3K36 methyltransferases, drastically altering H3K36 methyl states in cis and the binding of effector proteins with a PWWP domain, including DNMT3A/B. That confirms the existence of molecular commonalities amongst BLBS H3.3 point mutants while providing some of the first mechanistic insights into the syndrome.

molecular biology↗

bioRxiv2025

Integrated spatial proteomics of human PDAC uncovers an expanded tumour-immune-stroma spectrum with genomic associations

Distinctively, pancreatic ductal adenocarcinoma (PDAC) consists of sparse tumour lesions intertwined with extensive desmoplastic stroma. The complexity of tumour-microenvironment interactions within this desmoplasia poses a challenge for accurate tumour profiling and patient stratification, and characterizes a profoundly chemoresistant tumour. Here we mapped the spatial relationships between tumour, stroma, and immune cell compartments delineating tumour and microenvironment types that expand the classical to basal spectrum of human PDAC. We used imaging mass cytometry to profile the in situ multi-cellular organization of 81 cell types in resected cases with paired whole genome sequencing. Cell types, functions, and pathway activation were distributed as highly reproducible environments in discrete locations throughout these tumours, which we deep-profiled using laser-capture mass spectrometry. We show that the connections between tumour phenotypes, vascularization, immune response, and stromal biophysical state are reinforced by genomic aberrations, altered by treatment, and associated with patient outcome. Predictive machine-learning models showed that spatial single cell data outperformed genomic or clinical features but integrated multi-omics models provide the best prediction of patient survival with compressed models requiring only 10 non-redundant robust molecular measures associated with the phenotypic spectrum of PDAC. Together, these findings define a phenotypic and molecular framework of PDAC that captures tumour-microenvironment co-dependencies and offers a refined basis for patient stratification and therapeutic targeting.

cancer biology↗

bioRxiv2025

Multiple FGFR1 mutations modulate tumorigenic mechanisms in glioneuronal tumors.

FGFR1 genetic alterations are associated with human diseases, including brain tumors. We reported multiple FGFR1 mutations in familial and sporadic cases of low-grade glioneuronal tumors, suggesting intrinsic mechanisms of selective pressure toward FGFR1 multiple events arising in the context of a quiet genome. To decipher the molecular mechanisms triggered by multiple FGFR1 mutations, we have mapped the proximal interactome of wild-type, single-and double-mutant FGFR1 proteins through a BioID-MS approach. Our data reveals novel oncogenic functionality for the two hotspots N546K and K656E, linked to evasion of lysosomal degradation. We identified a modulatory role played by the susceptibility variant R661P, which hampers the oncogenic potential of both hotspot mutations by rescuing receptor degradation and reducing N546K affinity for the downstream effector PLC{gamma}. The R661P variant alone abolished the self-renewal capacity of oligodendroglioma cells and showed downregulation of genes involved in neurodevelopment and neuro-glial cell fate decisions, both aspects overcome in the double mutants. This study sheds light on the oncogenic effects associated with FGFR1 alterations and their recurrence in low-mutation burden and therapy naive tumors.

cancer biology↗

bioRxiv2024

The BLM-TOP3A-RMI1-RMI2 proximity map reveals that RAD54L2 suppresses sister chromatid exchanges

Homologous recombination is a largely error-free DNA repair mechanism conserved across all domains of life and is essential for the maintenance of genome integrity. Not only are the mutations in homologous recombination repair genes probable cancer drivers, some also cause genetic disorders. In particular, mutations in the Bloom (BLM) helicase cause Bloom Syndrome, a rare autosomal recessive disorder characterized by increased sister chromatid exchanges and predisposition to a variety of cancers. The pathology of Bloom Syndrome stems from the impaired activity of the BLM-TOP3A-RMI1-RMI2 (BTRR) complex which suppresses crossover recombination to prevent potentially deleterious genome rearrangements. We provide a comprehensive BTRR proximity interactome, revealing proteins that suppress crossover recombination. We find that RAD54L2, a SNF2-family protein, physically interacts with BLM and suppresses sister chromatid exchanges. RAD54L2 is important for recruitment of BLM to chromatin and requires an intact ATPase domain to promote non-crossover recombination. Thus, the BTRR proximity map identifies a regulator of recombination.

molecular biology↗

bioRxiv2024

High resolution cryo-EM of V-ATPase in native synaptic vesicles

Neurotransmitter release into the synaptic cleft between neurons enables the intercellular communication central to the function of the brain. In the presynaptic neuron, the proton pumping vesicular- or vacuolar-type ATPase (V-ATPase) powers neurotransmitter loading into synaptic vesicles (SVs), with the V1 complex dissociating from the membrane region of the enzyme before exocytosis. We isolated SVs from rat brain using SidK, a V-ATPase-binding bacterial effector protein. Single particle electron cryomicroscopy of the vesicles allowed high-resolution structure determination of V-ATPase within the native SV membrane. In the structure, regularly spaced cholesterol molecules decorate the enzymes rotor and the abundant SV protein synaptophysin binds the complex stoichiometrically. Conditions where ATP hydrolysis drives glutamate loading result in loss of V1 from the SV membrane, suggesting that SV loading is sufficient to induce V-ATPase dissociation.

biochemistry↗

bioRxiv2023

Trans-complementation by the RecB nuclease domain of RecBCD enzyme reveals new insight into RecA loading upon χ recognition

The loading of RecA onto ssDNA by RecBCD is an essential step of RecBCD-mediated homologous recombination. RecBCD facilitates RecA-loading onto ssDNA in a {chi}-dependent manner via its RecB nuclease domain (RecBn). Before recognition of {chi}, RecBn is sequestered through interactions with RecBCD. It was proposed that upon {chi}-recognition, RecBn undocks, allowing RecBn to swing out via a contiguous 70 amino acid linker to reveal the RecA-loading surface, and then recruit and load RecA onto ssDNA. We tested this hypothesis by examining the interactions between RecBn (RecB928-1180) and truncated RecBCD (RecB1-927CD) lacking the nuclease domain. The reconstituted complex of RecB1-927CD and RecBn is functional in vitro and in vivo. Our results indicate that despite being covalently severed from RecB1-927CD, RecBn can still load RecA onto ssDNA, establishing that RecBn does not function at the end of its flexible linker. Instead, RecBCD undergoes a {chi}-induced intramolecular rearrangement to reveal a RecA-loading surface.

biochemistry↗

bioRxiv2022

Comprehensive Interactome Mapping of the DNA Repair Scaffold SLX4 using Proximity Labeling and Affinity Purification

The DNA repair scaffold SLX4 has pivotal roles in cellular processes that maintain genome stability, most notably homologous recombination. Germline mutations in SLX4 are associated with Fanconi anemia, a disease characterized by chromosome instability and cancer susceptibility. The role of mammalian SLX4 in homologous recombination depends critically on binding and activating structure-selective endonucleases, namely SLX1, MUS81-EME1, and XPF-ERCC1. Increasing evidence indicates that cells rely on distinct SLX4-dependent complexes to remove DNA lesions in specific regions of the genome. Despite our understanding of SLX4 as a scaffold for DNA repair proteins, a detailed repertoire of SLX4 interactors has never been reported. Here, we provide the first comprehensive map of the human SLX4 interactome using proximity-dependent biotin identification (BioID) and affinity purification coupled to mass spectrometry (AP-MS). We identified 237 high-confidence interactors, of which the vast majority represent novel SLX4 binding proteins. Network analysis of these hits revealed pathways with known involvement of SLX4, such as DNA repair, and novel or emerging pathways of interest, including RNA metabolism and chromatin remodeling. In summary, the comprehensive SLX4 interactome we report here provides a deeper understanding of how SLX4 functions in DNA repair while revealing new cellular processes that may involve SLX4.

biochemistry↗

bioRxiv2022

Calcineurin associates with centrosomes and regulates cilia length maintenance

Calcineurin, or PP2B, the Ca2+ and calmodulin-activated phosphatase and target of immunosuppressants, has many substrates and functions that remain undiscovered. By combining rapid proximity-dependent labeling with cell cycle synchronization, we mapped calcineurins spatial distribution in different cell cycle stages. While calcineurin-proximal proteins did not vary significantly between interphase and mitosis, calcineurin consistently associated with multiple centrosomal/ciliary proteins. These include POC5, which binds centrin in a Ca2+-dependent manner and is a component of the luminal scaffold that stabilizes centrioles. We show that POC5 contains a calcineurin substrate motif (PxIxIT-type) that mediates calcineurin binding in vivo and in vitro. Using indirect immunofluorescence and expansion microscopy, we demonstrate that calcineurin co-localizes with POC5 at the centrosome, and further show that calcineurin inhibitors alter POC5 distribution within the centriole lumen. Our discovery that calcineurin directly associates with centrosomal proteins highlights a role for Ca2+ and calcineurin signaling at these organelles. Calcineurin inhibition promotes primary cilia elongation without affecting ciliogenesis. Thus, Ca2+ signaling within cilia includes previously unknown functions for calcineurin in cilia length maintenance, a process frequently disrupted in ciliopathies. Summary statementCalcineurin phosphatase participates in centrosome and cilia regulation. Calcineurin localizes to centrosomes, where it interacts with partner POC5, and its inhibition promotes cilia elongation.

cell biology↗

bioRxiv2022

Mapping Protein-Protein Interactions Using Data-Dependent Acquisition Without Dynamic Exclusion

Systematic analysis of affinity-purified samples by liquid chromatography coupled to mass spectrometry (LC-MS) requires high coverage, reproducibility, and sensitivity. Data-independent acquisition (DIA) approaches improve the reproducibility of protein-protein interaction detection by alleviating the stochasticity of data-dependent acquisition (DDA). However, the need for library generation and lack of multiplexing capabilities reduces their throughput, and analysis pipelines are still being optimized. In previous work using cell lysates, a fast MS/MS acquisition method with no dynamic exclusion (noDE) provided a comparable number of identifications and more accurate MS/MS intensity-based quantification than an optimized DDA method with dynamic exclusion (DE). Here, we have further optimized the noDE strategy for the analysis of protein-protein interactions and show that it provides better sensitivity and identifies more high confident interactors than the optimized DDA with DE and DIA approaches. TOC O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=107 SRC="FIGDIR/small/480563v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@553e5eorg.highwire.dtl.DTLVardef@71a722org.highwire.dtl.DTLVardef@193e7fborg.highwire.dtl.DTLVardef@1632e4b_HPS_FORMAT_FIGEXP M_FIG C_FIG

systems biology↗

bioRxiv2020

A SARS-CoV-2 - host proximity interactome

Viral replication is dependent on interactions between viral polypeptides and host proteins. Identifying virus-host protein interactions can thus uncover unique opportunities for interfering with the virus life cycle via novel drug compounds or drug repurposing. Importantly, many viral-host protein interactions take place at intracellular membranes and poorly soluble organelles, which are difficult to profile using classical biochemical purification approaches. Applying proximity-dependent biotinylation (BioID) with the fast-acting miniTurbo enzyme to 27 SARS-CoV-2 proteins in a lung adenocarcinoma cell line (A549), we detected 7810 proximity interactions (7382 of which are new for SARS-CoV-2) with 2242 host proteins (results available at covid19interactome.org). These results complement and dramatically expand upon recent affinity purification-based studies identifying stable host-virus protein complexes, and offer an unparalleled view of membrane-associated processes critical for viral production. Host cell organellar markers were also subjected to BioID in parallel, allowing us to propose modes of action for several viral proteins in the context of host proteome remodelling. In summary, our dataset identifies numerous high confidence proximity partners for SARS-CoV-2 viral proteins, and describes potential mechanisms for their effects on specific host cell functions.

systems biology↗

bioRxiv2020

SARS-CoV-2 spike glycoprotein vaccine candidate NVX-CoV2373 elicits immunogenicity in baboons and protection in mice

The COVID-19 pandemic continues to spread throughout the world with an urgent need for a safe and protective vaccine to effectuate herd immunity to control the spread of SARS-CoV-2. Here, we report the development of a SARS-CoV-2 subunit vaccine (NVX-CoV2373) produced from the full-length spike (S) protein, stabilized in the prefusion conformation. Purified NVX-CoV2373 S form 27.2nm nanoparticles that are thermostable and bind with high affinity to the human angiotensin-converting enzyme 2 (hACE2) receptor. In mice and baboons, low-dose NVX-CoV2373 with saponin-based Matrix-M adjuvant elicits high titer anti-S IgG that is associated with blockade of hACE2 receptor binding, virus neutralization, and protection against SARS-CoV-2 challenge in mice with no evidence of vaccine-associated enhanced respiratory disease (VAERD). NVX-CoV2373 vaccine also elicits multifunctional CD4+ and CD8+ T cells, CD4+ T follicular helper T cells (Tfh), and the generation of antigen-specific germinal center (GC) B cells in the spleen. These results support the ongoing phase 1/2 clinical evaluation of the safety and immunogenicity of NVX-CoV2327 with Matrix-M (NCT04368988).

microbiology↗

bioRxiv2019

A proximity biotinylation map of a human cell

Compartmentalization is a defining characteristic of eukaryotic cells, partitioning cellular processes into discrete subcellular locations. High throughput microscopy1 and biochemical fractionation coupled with mass spectrometry2-6 have helped to define the proteomes of a variety of organelles and macromolecular structures. However, many other intracellular compartments have remained refractory to such approaches, due for example to difficulty in purifying non-membrane bound structures. Proximity-dependent biotinylation techniques such as BioID provide an alternative approach for defining the composition of cellular compartments in living cells7-10. Here we present a BioID-based map of a human cell based on 192 markers from 32 different subcellular compartments, comprising 35,902 high confidence proximity interactions, and defining the intracellular locations of 4,145 unique proteins in HEK 293 cells. Our localization predictions meet or exceed previous-approaches, with higher specificity, and enabled the discovery of proteins at the mitochondrial outer membrane-endoplasmic reticulum (ER) interface that are critical for mitochondrial homeostasis. Based on this dataset, we have established humancellmap.org as a community resource that provides online tools for localization analysis of user BioID data, and demonstrate how this resource can be used to better understand BioID datasets.

molecular biology↗

bioRxiv2019

Systematic discovery of Short Linear Motifs decodes calcineurin phosphatase signaling

Short linear motifs (SLiMs) drive dynamic protein-protein interactions essential for signaling, but sequence degeneracy and low binding affinities make them difficult to identify. We harnessed unbiased systematic approaches for SLiM discovery to elucidate the regulatory network of calcineurin (CN)/PP2B, the Ca2+-activated phosphatase that recognizes LxVP and PxIxIT motifs. In vitro proteome-wide detection of CN-binding peptides, in vivo SLiM-dependent proximity labeling, and in silico modeling of motif determinants uncovered unanticipated CN interactors, including NOTCH1, which we establish as a CN substrate. Unexpectedly, CN shows SLiM-dependent proximity to centrosomal and nuclear pore complex (NPC) proteins - structures where Ca2+ signaling is largely uncharacterized. CN dephosphorylates human and yeast NPC proteins and promotes accumulation of a nuclear transport reporter, suggesting conserved NPC regulation by CN. The CN network assembled here provides a resource to investigate Ca2+ and CN signaling and demonstrates synergy between experimental and computational methods, establishing a blueprint for examining SLiM-based networks.

cell biology↗

bioRxiv2018

Endogenous BioID elucidates TCF7L1 interactome modulation upon GSK-3 inhibition in mouse ESCs

Modulation of Wnt target gene expression via the TCF/LEFs remains poorly understood. We employ proximity-based biotin labeling (BioID) to examine GSK-3 inhibitor effects on the TCF7L1 interactome in mouse ESCs. We generated ESC lines with biotin ligase BirA* fused to TCF7L1 by knocking it into the endogenous TCF7L1 locus or by inserting a doxinducible BirA*-TCF7L1 transgene into the Rosa26 locus. Induction yielded BirA*-TCF7L1 levels 3-fold higher than in the endogenous system, but substantial overlap in biotinylated proteins with high peptide counts were detected by each method. Known TCF7L1 interactors TLE3/4 and {beta}-catenin, and numerous proteins not previously associated with TCF7L1, were identified in both systems. Despite reduced BirA*-TCF7L1 levels, the number of hits identified with both BioID approaches increased after GSK-3 inhibition. We elucidate the network of TCF7L1 proximal proteins regulated by GSK-3 inhibition, validate the utility of endogenous BioID, and provide mechanistic insights into TCF7L1 target gene regulation.\n\nHighlightsO_LIBirA*-TCF7L1 at single-copy physiological levels generates robust BioID data\nC_LIO_LICHIR99021 reduces TCF7L1 levels but increases detectable TCF7L1-proximal proteins\nC_LIO_LIThe TCF7L1 interactome of largely epigenetic/transcription factors fluctuates with GSK-3 inhibition\nC_LIO_LIJMJD1C, SALL4 and BRG1/SMARCA4 are validated as TCF7L-interacting proteins\nC_LI

cell biology↗