Biology subjects

Wang, C.

Publications and source records attributed to Wang, C..

At least 91 records · Page 5Linked to original sources

bioRxiv2026

Nuclear Cx43 restrains microglial neurotoxicity during brain development

Microglia are essential for sculpting the developing brain, yet the molecular mechanisms that select beneficial overreactive phagocytosis remain incompletely understood. Connexin 43 (Cx43, encoded by GJA1 in humans) is best known as a gap junction and hemichannel protein, although its non-canonical, channel-independent functions are increasingly recognized. We found that Cx43 is highly expressed in microglia during the perinatal period in human and mouse, whereas proportion of full-length multimeric Cx43 unexpectedly localizes to the nucleoplasm. Deletion of microglial Cx43 in mice during development instigates a transient neurotoxic state with microgliosis, upregulated phagocytic and complement pathways, excessive neuronal apoptosis, translating into depressive-like and cognitive deficits in the adulthood. Notably, neither microglia-specific deletion of Cx43 in adulthood nor hemichannel blockade recapitulate these changes, indicating a channel-independent, developmental stage-specific neuroprotective mechanism. Nucleus-targeted Cx43 overexpression suppresses neurotoxic markers and neural apoptosis. Nuclear Cx43 interacts with transcriptional regulators to restrain proinflammatory gene programs, nuclear import of Cx43 is driven by neurogenic niche-derived bFGF, which triggers AKT-mediated phosphorylation of a C-terminal nucleus localization signal (NLS), 14-3-3 binding, and importin-dependent nucleus translocation. These findings reveal a developmentally restricted nuclear Cx43 function that restrains microglial neurotoxicity while promoting microglial physiological functions thus expanding connexin biology to transcriptional co-regulation and pointing to a potential avenue for therapeutic intervention.

neuroscience↗

bioRxiv2026

Single-Molecule Dwell Times in Biomolecular Condensates

Biomolecular condensates are dynamic, membrane-free compartments that continuously exchange molecules with their surroundings. The dwell time, defined as the time a molecule remains inside a condensate between entry and exit, determines how extensively the molecule can explore the dense phase and encounter potential binding partners or reaction sites, thereby modulating condensate function. Motivated by our single-molecule measurements of RNA dwell times, we developed an analytical theory to understand dwell-time distributions in biomolecular condensates. Our theory predicts that the dwell-time distributions generally exhibit an early-time power-law regime followed by a late-time exponential tail. The form of the distribution encodes the rate-limiting mechanism of molecular escape: dense-phase diffusion-limited transport feature a -1.5 power law with an exponential tail set by a diffusion timescale, whereas interfacial barrier-crossing-limited transport feature a - 0.5 power law with a decay governed by a barrier-crossing timescale. These distinct signatures provide a direct readout of the physical processes that control molecular retention in condensates, with implications for both natural and synthetic condensates.

biophysics↗

bioRxiv2026

Infection-Induced Dynamin-2 Repurposing Drives Podosome Maturation and Mechanical Immunity

Macrophages are the vanguard of innate immunity, relying on phagocytosis to clear invading pathogens. Podosomes in macrophages have recently emerged as mechanical structures that assemble at phagocytic cups to facilitate pathogen clearance. However, how these unique actin structures are regulated to execute antimicrobial functions remains poorly understood. Here, we reveal that fungal infection drives podosome maturation to strengthen macrophage mechanical immunity. Exposure to the opportunistic fungus Candida albicans upregulates the scaffold protein Tks5 and activates Src kinase, which repurposes dynamin-2 from a membrane fission enzyme into an actin-bundling protein. This functional switch stabilizes the podosome actin core, enhancing the adhesion and mechanical force generation required to efficiently engulf, fold, and trap invading fungi. Ultimately, our findings define a mechanobiological paradigm in which infection-induced molecular repurposing drives macrophage antifungal immunity.

cell biology↗

bioRxiv2026

Lineage-Specific Neofunctionalization of Polyacetylene-Directing UGT76 Glycosyltransferases in Campanulaceae

Polyacetylene glycosides exhibit notable pharmacological activities, yet the glycosyltransferases acting on their polyacetylene scaffolds remain unknown. Here we report a telomere-to-telomere genome assembly of Codonopsis pilosula and, guided by spatial metabolomics, characterize three UDP-glycosyltransferases: CpUGT76BG1 and CpUGT76BG2 catalyze the direct glycosylation of lobetyol to lobetyolin, while CpUGT94BY2 performs subsequent sugar-sugar coupling to produce lobetyolinin, with each activity confirmed by in planta overexpression. Structural modeling reveals that CpUGT76BG1 and CpUGT76BG2 employ a deep hydrophobic tunnel to fully encase the linear polyacetylene chain, a binding architecture distinct from the shallow pockets used by canonical plant UGTs for planar aromatic substrates. Ancestral sequence reconstruction across eleven nodes partitions the UGT76 lineage into three functionally distinct evolutionary stages, tracing the trajectory from an ancestral shallow pocket to this specialized deep architecture. These findings establish the key glycosylation steps of polyacetylene glycoside biosynthesis, define a tunnel-based paradigm for non-planar substrate recognition, and reveal how tandem duplication-driven active site remodeling generates metabolic novelty.

evolutionary biology↗

bioRxiv2026

Recognition Mechanism of Serotonin by a G-Quadruplex-Duplex Hybrid Aptamer

Serotonin is a key neurotransmitter, and aptamer-based tools using the 44-nt Apt44 have been successfully developed for its in vitro and in vivo detection. Nevertheless, the structural basis of recognition by this aptamer remains unclear. Here we report high-resolution NMR structures of Apt38, a 6-nt truncated variant in the third loop of Apt44, in free and serotonin-bound states. Both structures reveal a two-layered antiparallel chair-type G-quadruplex core with three edgewise loops and a terminal duplex, forming a G-quadruplex-duplex hybrid structure. Serotonin binds at the G-quadruplex-duplex junction, stabilized by stacking, electrostatic attraction, hydrogen bonding, and hydrophobic contacts. Apt38 is preorganized for binding, whereas the longer third loop of Apt44 introduces conformational dynamics into the G-quadruplex scaffold, which enables a pronounced binding-triggered conformational switch in PBS buffer, explaining its sensing mechanism. Our work reveals the recognition and sensing mechanism of the serotonin aptamer and provides a framework for aptamer design in serotonin biosensing.

biophysics↗

bioRxiv2026

Single-Cell Transcriptomic Analysis of the Immune Response to CHIKVInfection

BackgroundThe Chikungunya virus (CHIKV), a re-emerging mosquito-borne alphavirus, is responsible for acute febrile illness and severe polyarthralgia. Although both innate and adaptive immune responses influence the disease outcomes, the detailed cellular immunopathogenesis of CHIKV in peripheral blood is not yet fully elucidated. MethodsWe conducted single-cell RNA sequencing (scRNA-seq) on peripheral blood mononuclear cells (PBMCs) obtained from patients acutely infected with CHIKV and from healthy control subjects. Cellular interactions were inferred, and the transcriptomic results were orthogonally validated through quantitative real-time PCR (qPCR) and Enzyme-Linked Immunosorbent Assay (ELISA) to assess systemic interferon-stimulated responses. Furthermore, a comparative analysis was performed using publicly available single-cell data from Dengue virus (DENV) infections. ResultsCHIKV infection significantly altered the immune system, increasing monocytes and dendritic cells while reducing T and B lymphocytes. Monocytes and NK cells showed strong activation of interferon-stimulated genes (ISGs). Monocytes were identified as key in driving inflammatory and immune responses. In adaptive immunity, CHIKV led B cells to become plasmablasts with antiviral immunoglobulins and caused T cells and NK-like T cells to show signs of cytotoxicity and exhaustion. Validation showed increased levels of IFN-{gamma}, IFN-{beta}1, MX1, and ISG15. CHIKV triggered a more intense, monocyte-driven interferon response than DENV. ConclusionsAcute CHIKV infection induces a systemic interferon response predominantly centered on monocytes, accompanied by significant alterations in adaptive immunity. Circulating ISG products, including MX1 and ISG15, reflect the transcriptomic activation and may serve as potential biomarkers for assessing the early intensity of innate antiviral responses.

immunology↗

bioRxiv2026

Targeting Cellular Pseudo-Senescence to Overcome PARP inhibitors Resistance in BRCA1 -Mutated Breast Cancer

Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) are a mainstay therapy for homologous recombination (HR)-deficient cancers; however, resistance remains a major clinical challenge. Previously, through a genome wide CRISPR screen, we identified ZNF251 haploinsufficiency as a novel driver of PARPi resistance. In BRCA1-mutant (BRCA1mut) cells, ZNF251 deficiency led to HR hyperactivation, conferring PARPi resistance that could be reversed by RAD51 inhibition. In this study, we further show that ZNF251 deficiency induces replication stress and a pseudo-senescence state, in which cells exhibit molecular and phenotypic markers of senescence while retaining proliferative capacity. Because senomorphic and senolytic therapies can target senescent cells, we tested whether these approaches could overcome PARPi resistance in ZNF251-deficient breast cancer cells. Critically, targeting this senescence-like state with either senomorphic agents, such as cytokine inhibitors, or senolytic agents, such as BCL-2 and BCL-XL inhibitors, overcame PARPi resistance ex vivo and in vivo. Importantly, pseudo-senescence was also observed in other PARPi-resistant contexts driven by HR hyperactivation, including 53BP1- and Shieldin-mutant cells, suggesting that it may represent a broader mechanism underlying PARPi resistance in breast cancer. Furthermore, in two olaparib-resistant, BRCA-mutant triple-negative breast cancer organoid models, treatment with DT2216, a BCL-XL-targeting PROTAC, sensitized both models to olaparib. Together, our work defines a novel pathway linking HR hyperactivation, replication stress, and pseudo-senescence, and positions both senomorphic and senolytic therapies as promising strategies to overcome PARPi resistance in BRCA1mut breast cancer. HighlightsO_LIZNF251 deficiency drives PARP inhibitor resistance through HR hyperactivation, replication stress, and pseudo-senescence in BRCA1-mutant breast cancer. C_LIO_LISenomorphic and senolytic therapies overcome PARP inhibitor resistance in vitro, in vivo, and in patient-derived organoid models. C_LIO_LIPseudo-senescence represents a shared vulnerability of HR-hyperactivated PARPi-resistant cancers and can be therapeutically targeted. C_LI

Cancer Biology↗

bioRxiv2026

High-Throughput Screening Identifies Small-Molecule Inhibitors of the Tau-LRP1 Interaction

The cellular uptake and propagation of tau are central features of tauopathies, including Alzheimers disease, and are mediated by the endocytic receptor low-density lipoprotein receptor-related protein 1 (LRP1). While prior studies have implicated LRP1 in tau binding and internalization, the biochemical features of this interaction and its suitability for therapeutic targeting remain incompletely defined. Here, we establish a quantitative and scalable framework to interrogate the tau-LRP1 interaction and identify small-molecule modulators. We engineered and purified the LRP1 ligand-binding domain 4 (BD4), a key region mediating tau interaction, and developed multiple orthogonal assays, including fluorescence polarization, split luciferase complementation, and time-resolved FRET, to measure LRP1-BD4 interactions with tau and a known peptide ligand. Across assay formats, we observe consistent binding affinities in the nanomolar range and demonstrate competitive displacement by tau, receptor-associated protein (RAP), and a peptide ligand, supporting overlapping binding interfaces. Leveraging these platforms, we performed small molecule high-throughput screening and identified a set of candidate inhibitors of the LRP1-BD4-tau interaction. Selected compounds reduced tau uptake in a cellular assay, phenocopying competitive inhibition by tau and a peptide ligand. Together, these studies define the LRP1-BD4-tau interaction as a biochemically tractable and druggable interface and establish an integrated discovery pipeline linking mechanistic characterization to functional cellular outcomes. This work provides a foundation for the development of therapeutic strategies targeting LRP1-mediated tau uptake.

biochemistry↗

bioRxiv2026

Prenatal e-cigarette exposure induces region- and cell type-specific metabolic and developmental reprogramming

Prenatal e-cigarette exposure (PeCE) is increasingly prevalent and has been associated with adverse neurodevelopmental outcomes, yet how maternal vaping perturbs early brain development remains poorly understood. We integrated spatial transcriptomics, snRNA-seq and lipidomics to define neonatal rat brain responses to PeCE in rats at regional and cellular resolution. PeCE induced pronounced spatial heterogeneity in vulnerability, with the striatum exhibiting the strongest developmental transcriptional disruption. PeCE disrupts lipid metabolic homeostasis and induced molecular signatures suggestive of enhance Ca2+ signaling, dopaminergic responsiveness and region-specific synaptic stress programs. In the striatum, PeCE induced transcriptional programs consistent with altered lipid utilization, silent synapse-like molecular features, suppressed dendritic spine development and delayed D1-medium spiny neuron maturation. PeCE-sensitive genes were enriched in human autism spectrum disorders and neurodevelopment risk loci. Together, these findings identify disrupted metabolic and developmental reprogramming as a central feature of neonatal brain vulnerability to maternal vaping and provide a mechanistic framework linking PeCE to neurodevelopmental disease risk.

neuroscience↗

bioRxiv2026

Ciz1 safeguards Drosophila wing development by suppressing oxidative stress

Cell proliferation and fate specification are fundamental processes that ensure the generation of organs with proper size and patterning. Oxidative stress caused by accumulation of reactive oxygen species (ROS) can lead to cell cycle arrest, senescence, cell death and cell fate misspecification, thereby impairing normal development and contributing to many pathological processes. In this study, we identify Drosophila Ciz1 as a critical factor that safeguards epithelial homeostasis and development by preventing oxidative stress. Knockdown of Ciz1 in the Drosophila wing imaginal disc, an epithelial tissue that serves as the larval precursor of the adult wing, results in a small wing phenotype accompanied by thickened and ectopic veins. We further demonstrate that reduced Ciz1 expression leads to accumulation of donut-shaped mitochondria and elevated ROS levels. The increased oxidative stress subsequently suppresses proliferation via activation of JNK and promotes excessive vein formation by upregulating Rhomboid, a positive regulator of EGFR signaling. Interestingly, although Ciz1 is a zinc finger protein that predominantly localizes to the nucleus, neither its zinc finger motifs nor its nuclear localization is required for suppression of oxidative stress. Instead, the prion-like domain in its N-terminal part is essential for this activity. Our work identifies Ciz1 as an important factor in preventing oxidative stress and maintaining epithelial homeostasis.

Developmental Biology↗

bioRxiv2026

A complete RXFP1-relaxin interaction model unlocks the design of potent mini-protein modulators

Relaxin family peptide receptor 1 (RXFP1) is a multi-domain GPCR with compelling therapeutic potential, yet uncertainty surrounding the mechanism of its activation by the hormone H2 relaxin has hindered the development of selective modulators. Here, we combine deep learning based structural modelling with de novo protein design to overcome this barrier. We generate a high-confidence structural model of the RXFP1-relaxin complex that is strongly supported by existing biochemical and functional evidence. This model reveals that relaxin engagement stabilises the RXFP1 extracellular linker, thereby triggering receptor activation. Guided by this model, we design mini-protein modulators that either block linker stabilisation or enforce it and induce an active receptor geometry. These molecules act as potent, selective RXFP1 antagonists or agonists, achieving low-nanomolar activity in both engineered and endogenously expressing cell lines despite adopting folds unrelated to relaxin. Together, these findings define the mechanistic basis of RXFP1 signalling, establish the first de novo agonists and antagonists of this receptor, and demonstrate how AI-enabled modelling and design can target structurally complex GPCRs previously inaccessible to structure-guided drug discovery.

biochemistry↗

bioRxiv2026

Human cardiomyocytes with trisomy 21 exhibit heightened susceptibility and immunological response to SARS-CoV-2 infection

Coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, is associated with significant cardiovascular complications, including myocardial injury and long-term cardiac dysfunction. Individuals with Down syndrome (trisomy 21) exhibit increased susceptibility to severe COVID-19 outcomes, yet the cardiomyocyte-intrinsic mechanisms underlying this vulnerability remain poorly understood. To investigate genotype-specific responses to SARS-CoV-2 infection, we generated induced pluripotent stem cell-derived cardiomyocytes from individuals with trisomy 21 and their euploid, sex-matched biological relatives. Cardiomyocytes were inoculated with SARS-CoV-2, and viral susceptibility was assessed by immunofluorescence. Bulk RNA sequencing was performed under baseline and infected conditions to define transcriptional programs associated with viral response. Trisomy 21 iPSC-CMs exhibited increased susceptibility to SARS-CoV-2 infection, with greater viral protein expression and a higher proportion of infected cardiomyocytes compared to controls. Baseline transcriptomic analysis revealed no significant differences in canonical viral entry factors including ACE2 and TMPRSS2, suggesting that differential susceptibility is not driven by entry receptor availability. Following infection, both trisomy 21 and euploid control groups activated conserved antiviral pathways; however, trisomy 21 cardiomyocytes displayed a markedly amplified transcriptional response, with substantially greater numbers of differentially expressed genes. Upregulated pathways included interferon signaling, NF-{kappa}B activation, cytokine and chemokine signaling, and innate immune responses, while downregulated pathways were enriched for cardiomyocyte structural integrity, calcium handling, and metabolic processes. Notably, inflammatory and cytokine-related transcripts were significantly more elevated in trisomy 21 cells, consistent with an exaggerated immune response. These findings provide mechanistic insight into the increased cardiovascular risk observed in individuals with Down syndrome and highlight dysregulated immune signaling as a potential therapeutic target in this high-risk population.

Cell Biology↗

bioRxiv2026

Cryo-EM structure of human LRRC15 reveals the basis of therapeutic antibody recognition

Leucine-rich repeat containing 15 (LRRC15) is a structural uncharacterised membrane protein, which is highly upregulated in cancer-associated fibroblasts and enriched in desmoplastic tumours including pancreatic, breast and head-and-neck cancers, where it is associated with therapy resistance. The LRRC15-targeting antibody-drug conjugate samrotamab vedotin has advanced into Phase I clinical evaluation, yet mechanistic understanding of how samrotamab engages its target has remained elusive in the absence of structural data. Here, using hydrogen-deuterium exchange mass spectrometry and cryo-electron microscopy, we define the samrotamab epitope on LRRC15 and determine the structure of the LRRC15-samrotamab complex to 2.6 [A] resolution - the first high-resolution structure of this receptor. Samrotamab engages a membrane-proximal epitope within the C-terminal leucine-rich repeat region, leaving the canonical concave surface fully exposed for potential interactions. The lateral binding mode of samrotamab and the open arc geometry of LRRC15 provide a structural rationale for why antibody occupancy may leave signalling-competent surfaces intact. Guided by these insights, we computationally designed minibinders targeting the concave surface, identifying multiple binders with nanomolar affinity. Together, our work establishes the first structural framework for LRRC15, defines the molecular basis of therapeutic antibody recognition, and identifies the concave surface as a promising target for next-generation LRRC15-directed therapeutics.

biochemistry↗

bioRxiv2026

Steller: a high-resolution platform for spatial clonal tracing of mammalian brain development

Resolving both lineage history and spatial position at single-cell resolution is essential for understanding how tissue assemble, yet simultaneously interrogation of both dimensions remains technically challenging. Here, we present Steller (Spatio-temporal cell lineage tracker), an integrated experimental and computational framework that overcomes the sensitivity bottleneck limiting lineage barcode detection in high-resolution spatial transcriptomics (ST). By co-depositing capture probes alongside conventional poly(T) oligonucleotides on high-density spatial arrays, Steller achieves targeted enrichment of lineage barcodes at spatial single cell resolution. Applied to clonally labeled embryonic day 12.5 (E12.5) mouse forebrain development harvested at postnatal day 4 (P4), Steller increased the proportion of barcode-detectable cells and recovered higher clonal diversity compared with poly(T) chip. Leveraging this enhanced sensitivity, we resolved distinct spatial clonal architectures across three forebrain regions: horizontal or radial-to-horizontal transitions in hippocampal pyramidal neurons, dorsoventrally restricted yet multi-nuclei spread in thalamus, and fate-restricted spiny projection neuron lineages. Steller establishes a generalizable strategy for lineage-enhanced spatial profiling compatible with existing high-resolution spatial transcriptomics platforms and adaptable to diverse biologic process, providing a framewrok for investigating lineage-dependent tissue organization. HighlightsO_LISteller integrates targeted lineage-barcode enrichment with high-resolution spatial transcriptomics C_LIO_LISteller substantially improves clonal detection sensitivity at single-cell resolution C_LIO_LISteller reveals region-specific spatial clonal architectures across the developing mouse forebrain C_LI

Developmental Biology↗

bioRxiv2026

Homeobox transcription factor MSX2 down-regulates ERα action to facilitate anti-estrogensensitivity in ERα+ breast cancer

Breast cancer is the most common malignancy among women worldwide. Estrogen receptor (ER)-positive breast cancer is about 70% in the total breast cancer. It has variable prognosis and high recurrent risk, frequently developing resistance to endocrine therapies. Herein, we have identified that a homeobox transcription factor MSX2 downregulated in ER-positive breast cancer is correlated with the advanced grade and poor survival outcomes. Our results have demonstrated that MSX2 interacts with ER to inhibit ER-mediated transactivation. Mechanistically, MSX2 associates with HDAC1/HDAC2 to form a protein complex. MSX2 is required for recruitment of HDAC1/HDAC2 complex to estrogen response elements (EREs) region on ER downstream target genes, reducing histone H3K9ac and H3K27ac levels to inactivate gene transcription. Functionally, ectopic expression of MSX2 suppresses cell growth and enhances the sensitivity to anti-estrogen treatment in ER-positive breast cancer cells. Our results indicate that MSX2 as a novel co-repressor of ER is involved in suppression of ER-positive breast cancer progression. Restoring MSX2 protein may provide a promising strategy to overcome endocrine resistance in ER-positive breast cancer.

Molecular Biology↗

bioRxiv2026

Robust integration of weakly anchored spatial multi-omics

Spatial multi-omics holds great promise for dissecting complex biological processes, though inherent technical constraints continue to limit its widespread adoption. Currently, most studies therefore measure distinct omics features on separate tissue sections, necessitating spatial diagonal integration. An emerging practical solution is to leverage hematoxylin and eosin (H&E) images as an integration anchor, given their ubiquity, low cost, and compatibility across tissue preparations. However, this anchor is frequently compromised in real-world settings by variations in H&E staining style, absence of reliable histological landmarks, and mismatches in spatial resolutions across omics modalities. To address this, we introduce SpaWeaver, a computational framework that couples a pathology foundation model with a graph Transformer and a latent feature aligner module, providing a highly robust solution for weakly anchored spatial omics data diagonal integration. Extensive experiments demonstrate that SpaWeaver exhibits superior robustness against isolated or synergistic weak-anchoring factors. The spatial multi-omics profiles generated by SpaWeaver link molecular features originally separated on two sections, unlocking diverse downstream analyses once exclusive to co-assayed spatial multi-omics data, including niche-aware cell-cell communication inference and multi-omics resolved cell state. In this study, it unveils tumor-distance-dependent fibroblast-CD4{square}T-cell signaling in human colon adenocarcinoma and identifies a hypoxic glycolytic tumor state with pyknotic nuclei in human ovarian cancer. Overall, our approach bridges readily accessible single-omics measurements across weakly anchored tissue sections, enabling unified spatial multi-omics characterization and system-level tissue analysis.

bioinformatics↗

bioRxiv2026

Glioblastoma-derived extracellular vesicles released after radiation promote cognitive impairment through NFκB-mediated microglial activation

Glioblastoma (GBM) is the most aggressive primary brain tumor in adults. Cognitive impairment is a common sequela in glioblastoma survivors, yet the underlying mechanisms remain poorly understood. Extracellular vesicles (EVs) derived from glioblastoma are established mediators of intercellular signaling within the tumor microenvironment. Here, we investigated whether GBM-derived EVs released after radiation treatment (RT-EVs) regulate cognitive function. Treatment with RT-EVs was associated with cognitive deficits and neuroinflammatory responses in vivo. In vitro, RT-EVs activated the NF{kappa}B pathway and induced the release of neurotoxic H2O2. Importantly, NF{kappa}B p50 knockdown abolished the H2O2 release previously triggered by RT-EVs, demonstrating mechanistic dependence on NF{kappa}B signaling. Collectively, these findings identify GBM-derived RT-EVs as critical mediators of cognitive impairment through NF{kappa}B-dependent redox imbalance. EV-driven redox dysregulation may therefore represent a therapeutic target to mitigate GBM-associated cognitive dysfunction. Highlights- Radiation induces the release of glioblastoma-derived EVs that are biologically different from those released under non-irradiated conditions. - EVs released from glioblastoma after radiation are sufficient to impair cognition - EVs from irradiated glioblastoma can activate microglia via NF{kappa}B and induce production of neurotoxic H2O2 Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=52 SRC="FIGDIR/small/730969v1_ufig1.gif" ALT="Figure 1"> View larger version (11K): org.highwire.dtl.DTLVardef@e57bcborg.highwire.dtl.DTLVardef@228862org.highwire.dtl.DTLVardef@127dd13org.highwire.dtl.DTLVardef@232ddd_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2026

Uracil/guanine mismatches trigger MutS HOMOLOG1-dependent mitochondrial DNA double-strand breaks in Arabidopsis

Angiosperm mitochondrial genomes exhibit exceptionally low nucleotide substitution rates, likely supported by active homologous recombination-mediated repair, while maintaining genome integrity by suppressing illegitimate recombination between imperfectly matched sequences that could otherwise cause deleterious structural rearrangements. The nuclear-encoded MutS HOMOLOG1 (MSH1) protein has been proposed to help resolve this paradox by recognizing mismatches and promoting DNA double-strand break-associated repair responses that suppress both point mutations and illegitimate recombination. However, direct experimental evidence for this proposed activity of MSH1 has been lacking. Here, we demonstrate that targeted base editing using a mitochondrial TALE-cytidine deaminase fusion (mitoTALECD) in Arabidopsis mitochondria induces deletions at the redundant gene atp6-2. These deletions phenocopy those generated by mitochondria-targeted TALEN (mitoTALEN) cleavage at the same locus. Notably, deletion events that encompass the base-editing target site were markedly reduced in msh1 mutant backgrounds, indicating that functional MSH1 promotes their formation. In vitro assays further demonstrated that recombinantly expressed MSH1 efficiently recognizes U:G mismatches derived from deoxycytidine-to-deoxyuridine deamination events and performs coordinated double incisions, thereby generating staggered dsDNA breaks with short 3' overhangs. Together, these findings provide direct experimental support for the long-postulated role of MSH1: the induction of mismatch-triggered DNA double-strand breaks. This MSH1 activity likely promotes the repair of mismatched bases and prevents illegitimate recombination by rejecting annealing between imperfect repeat sequences, thereby helping maintain the characteristic mutational stasis and recombinational dynamics of angiosperm mitochondrial genomes.

Plant Biology↗