Biology subjects

Chen, Z. J.

Publications and source records attributed to Chen, Z. J..

12 recordsLinked to original sources

bioRxiv2026

Vibrio parahaemolyticus metabolically adapts while tempering the host immune response during host cell invasion.

Vibrio parahaemolyticus (V. para) is an enteric pathogen that establishes a protected intracellular niche using its second type III secretion system. However, how this bacterium adapts to the host cytoplasm while overcoming cellular defenses has remained unclear. To define these mechanisms, we performed dual-transcriptomic profiling of both pathogen and host during invasion, intracellular replication, and late infection. Our analyses revealed extensive metabolic reprogramming by V. para, including induction of diverse nutrient transporters and metabolic pathways. We discovered that because mammalian cells are auxotrophic for aromatic amino acids, V. para must activate its own unique biosynthetic machinery, a requirement that proved essential for intracellular growth. Infected host cells mounted a sustained NF-kappaB response. Both heightened NF-kappaB activation and disruption of canonical NF-kappaB signaling restricted bacterial expansion, indicating that V. para exploits a finely tuned Goldilocks level of immune signaling to promote survival and replication. Together, these findings uncover fundamental metabolic and immune adaptations that drive pathogenesis.

microbiology↗

bioRxiv2026

Innate immune sensing via the cGAS-STING pathway restricts extrachromosomal DNA-driven tumorigenesis

Extrachromosomal DNAs (ecDNAs) are circular DNA fragments frequently found in human cancers, where they amplify oncogenes, drive tumor heterogeneity, and promote therapy resistance and poor prognosis. Despite their prevalence, how ecDNAs interact with the immune system remains poorly understood. Here, we show that the cytosolic DNA sensor cGAS detects ecDNA fragments in the cytoplasm and activates the innate immune response. cGAS and STING are frequently silenced in ecDNA+ tumors through promoter hypermethylation. Restoring cGAS or STING in human and murine ecDNA+ cancer cells reactivates innate immune signaling and selectively suppresses ecDNA+ tumor growth in an immunocompetent mouse model. Using two ecDNA biogenesis models, we show that the cGAS-STING pathway restricts de novo ecDNA formation. Together, our findings identify innate immune sensing as a natural barrier to ecDNA-driven oncogenesis and establish cGAS-STING reactivation as a therapeutic strategy for ecDNA+ cancers. HighlightsO_LIThe cGAS-STING pathway is frequently silenced in ecDNA+ tumors C_LIO_LIRestoration of cGAS in ecDNA+ cells activates innate immune responses C_LIO_LIcGAS expression suppresses ecDNA+ tumor growth in vivo C_LIO_LIThe cGAS-STING pathway restricts de novo ecDNA biogenesis C_LI

cancer biology↗

bioRxiv2025

PtdIns(3,5)P2 Is an Endogenous Ligand of STING in Innate Immune Signaling

Cytosolic DNA exposure triggers innate immune responses through cyclic GMP-AMP (cGAMP) synthase (cGAS)1-3. Upon binding to DNA, cGAS is activated to produce cGAMP, which functions as a second messenger that binds to stimulator of interferon genes (STING), an endoplasmic reticulum (ER)-localized signaling adaptor3-5. STING then traffics from the ER to the Golgi, leading to activation of the kinases TBK1 and IKK and subsequent induction of interferons and other cytokines6-10. Here we show that phosphatidylinositol 3,5-bisphosphate [PtdIns(3,5)P2] is an endogenous ligand of STING that functions together with cGAMP to induce STING activation. Proteomics analysis identified a constitutive interaction between STING and PIKfyve, an enzyme that produces PtdIns(3,5)P2 in mammalian cells. Deletion of PIKfyve blocked STING trafficking from the ER and TBK1 activation. In vitro reconstitution revealed a strong and selective effect of PtdIns(3,5)P2 on STING activation. Purified STING bound directly to PtdIns(3,5)P2 in a fluorescence resonance energy transfer (FRET) assay. Consistently, PtdIns(3,5)P2 promoted cGAMP-induced STING oligomerization by binding to a groove between STING dimers as revealed by cryo-EM (Li et al., co-submitted). Similar to PIKfyve depletion, mutation of the PtdIns(3,5)P2-binding residues in STING blocked its trafficking and downstream signaling. These results reveal PtdIns(3,5)P2 as a lipid ligand of STING with essential roles in innate immunity.

biochemistry↗

bioRxiv2025

Regulation of STING activation by phosphoinositide and cholesterol

Stimulator of interferon genes (STING) is an essential adaptor in the cytosolic DNA sensing innate immune pathway. STING is activated by cyclic-GMP-AMP (cGAMP) produced by the DNA sensor cGAMP synthase (cGAS). cGAMP-induced high-order oligomerization and translocation of STING from the endoplasmic reticulum to Golgi and post-Golgi vesicles are critical for STING activation. Recent studies have shown that phosphatidylinositol phosphates (PIPs) and cholesterol also play important roles in STING activation, but the underlying mechanisms remain unclear. Here, we demonstrate that cGAMP-induced high-order oligomerization of STING is enhanced strongly by PI(3,5)P2 and PI(4,5)P2, and by PI(4)P to a less extent. Our cryo-EM structures reveal that PIPs together with cholesterol bind at the interface between STING dimers, directly promoting the high-order oligomerization. The structures also provide an explanation for the preference of the STING oligomer to different PIPs. Mutational and biochemical analyses confirm the binding modes of PIPs and cholesterol and their roles in STING activation. Our findings shed light on the regulatory mechanisms of STING by specific lipids, which may underlie the role of intracellular compartment trafficking in dictating STING signaling.

immunology↗

bioRxiv2025

ecDNA-driven oncogene super-expressors shape immunoevasive tumor microenvironment

ecDNA contributes to cancer genetic heterogeneity through random segregation during mitosis. Emerging evidence links ecDNA to immune evasion, but the mechanism remains elusive. Using genetically engineered mouse models of pancreatic ductal adenocarcinoma (PDAC), we show that Kras and Myc oncogenes are amplified either on ecDNAs or as homogeneously staining regions (HSRs) on chromosomes. ecDNA-driven tumors are more aggressive in immunocompetent mice. Single-cell transcriptomic and histological analyses reveal that ecDNA-driven tumors rapidly establish an immunoevasive tumor microenvironment (TME), marked by increased myofibroblastic cancer-associated fibroblasts (myCAFs) and reduced T cell infiltration. Mechanistically, ecDNA heterogeneity generates a subset of cancer cells with extremely high Kras expression, termed super-expressors, which secrete amphiregulin to promote myCAF expansion and suppress T cell infiltration. Clonally organized super-expressors establish an immunoevasive niche in the TME from patients with PDAC. Our findings demonstrate a causal role of ecDNA in TME remodeling, offering insights into cancer heterogeneity and immune evasion.

cancer biology↗

bioRxiv2025

Integrated ambient modeling and genetic demultiplexing of single-cell RNA+ATAC multiome experiments with Ambimux

Single cell technologies have advanced at a rapid pace, providing assays for various molecular phenotypes. Droplet-based single cell technologies, particularly those based on nuclei isolation, such as simultaneous RNA+ATAC single-cell multiome, are susceptible to exogenous ambient molecule contamination, which can increase noise in cell type-level associations. We reasoned that genotype-based sample multiplexing can provide an opportunity to infer this ambient contamination by leveraging DNA variation in sequenced reads. Thus, we developed ambimux, a likelihood-based method to estimate ambient fractions and demultiplex single-cell multiome experiments using genotype-level data. Ambimux models the ambient or nuclear probability at the read level and thus can classify empty droplets and estimate droplet-specific ambient molecule fractions in each modality. We first evaluated our method using simulated data sets across a range of parameters. We found that ambimux closely estimated the ground truth droplet contamination fractions in the RNA (MAE=0.048) and ATAC (MAE=0.042) modalities. As a result, ambimux maintained high specificity (>95%) and was able to correctly assign singlets at considerably high ambient fractions (up to 60%) for both RNA and ATAC modalities. In comparison with models that do not consider ambient contamination, these only maintained similar sensitivity levels at considerably lower ambient fractions (up to 25%). We then generated a real data set of seven visceral adipose tissue biopsies run on a single 10x Multiome channel. We ran ambimux and detected 4,986 singlets, capturing similar numbers as other methods. Then, we sought to evaluate the fidelity of the ambient fraction estimates from ambimux. We split singlets into ambient-enriched (>5% contamination in both modalities) or nuclear-enriched (<5% in both) droplets and performed gene-peak linkage analysis. Low ambient droplets resulted in more significant hits with gene-peak links enriched at the transcription start site relative to high ambient droplets, suggesting that the ambient droplets identified by ambimux hamper the identification of biologically meaningful signals. In summary, we developed a joint single-cell multiome demultiplexing method, ambimux, that accurately models and estimates ambient molecule contamination in each modality.

bioinformatics↗

bioRxiv2025

KDM5 demethylases suppress R-loop-mediated viral mimicry and DNA damage in breast cancer cells

Tumors with low expression of Interferon-Stimulated Genes (ISG) and Antigen Presentation (AP) genes respond relatively poorly to current immunotherapies. One of the early hallmarks of cancer is DNA hypomethylation in genomic repeat regions, resulting in the expression of normally silenced endogenous "viral" elements. Such epigenetic changes have the potential to augment anti-tumor immune responses as well as reduce tumor cell fitness through the generation of aberrant nucleic acid species (NAS) and consequent activation of NAS-sensing pathways. Therefore, tumor evolution should favor additional selective events that suppress NAS generation, possibly yielding specific therapeutic vulnerabilities. Here, we show that the Lysine Demethylase 5 (KDM5) family of epigenetic regulatory enzymes suppress R-loop formation in genomic repeat regions in cancer cells. We find that KDM5 inhibition in luminal breast cancer cells results in R-loop-mediated DNA damage, reduced cell fitness and an increase in ISG and AP signatures as well as cell surface Major Histocompatibility Complex (MHC) class I, mediated by RNA:DNA hybrid activation of the CGAS/STING pathway. KDM5 inhibition does not result in DNA damage or activation of the CGAS/STING pathway in normal breast epithelial cells, suggesting that KDM5 inhibitors may enable a wide therapeutic window in this setting, as compared to STING agonists or Type I Interferons. These findings provide new insights into the interplay between epigenetic regulation of genomic repeats, R-loop formation, innate immunity, and cell fitness in the context of cancer evolution and therapeutic vulnerability.

cancer biology↗

bioRxiv2024

Single-cell DNA methylome and 3D genome atlas of the human subcutaneous adipose tissue

Human subcutaneous adipose tissue (SAT) contains a diverse array of cell-types; however, the epigenomic landscape among the SAT cell-types has remained elusive. Our integrative analysis of single-cell resolution DNA methylation and chromatin conformation profiles (snm3C-seq), coupled with matching RNA expression (snRNA-seq), systematically cataloged the epigenomic, 3D topology, and transcriptomic dynamics across the SAT cell-types. We discovered that the SAT CG methylation (mCG) landscape is characterized by pronounced hyper-methylation in myeloid cells and hypo-methylation in adipocytes and adipose stem and progenitor cells (ASPCs), driving nearly half of the 705,063 detected differentially methylated regions (DMRs). In addition to the enriched cell-type-specific transcription factor binding motifs, we identified TET1 and DNMT3A as plausible candidates for regulating cell-type level mCG profiles. Furthermore, we observed that global mCG profiles closely correspond to SAT lineage, which is also reflected in cell-type-specific chromosome compartmentalization. Adipocytes, in particular, display significantly more short-range chromosomal interactions, facilitating the formation of complex local 3D genomic structures that regulate downstream transcriptomic activity, including those associated with adipogenesis. Finally, we discovered that variants in cell-type level DMRs and A compartments significantly predict and are enriched for variance explained in abdominal obesity. Together, our multimodal study characterizes human SAT epigenomic landscape at the cell-type resolution and links partitioned polygenic risk of abdominal obesity to SAT epigenome.

genomics↗

bioRxiv2023

Imprinting but not cytonuclear interactions affects parent-of-origin effect on seed size in Arabidopsis hybrids

The parent-of-origin effect on seed size can result from imprinting or a combinational effect between cytoplasmic and nuclear genomes, but their relative contributions remain unknown. To discern these confounding effects, we generated cytoplasmic-nuclear substitution (CNS) lines using recurrent backcrossing in the Arabidopsis thaliana ecotypes Col-0 and C24. These CNS lines differ only in the nuclear genome (imprinting) or in the cytoplasm. The CNS reciprocal hybrids with the same cytoplasm display a [~]20% seed size difference as observed in the conventional hybrids. However, seed size is similar between the reciprocal cybrids with fixed imprinting. Transcriptome analyses in the endosperm of CNS hybrids using laser-capture microdissection have identified 104 maternally expressed genes (MEGs) and 90 paternally-expressed genes (PEGs). These imprinted genes are involved in pectin catabolism and cell wall modification in the endosperm. HDG9, an epiallele and one of 11 cross-specific imprinted genes, controls seed size. In the embryo, a handful of imprinted genes is found in the CNS hybrids but only one is expressed higher in the embryo than endosperm. AT4G13495 encodes a long-noncoding RNA (lncRNA), but no obvious seed phenotype is observed in the lncRNA knockout lines. NRPD1, encoding the largest subunit of RNA Pol IV, is involved in the biogenesis of small interfering RNAs. Seed size and embryo is larger in the cross using nrpd1 as the maternal parent than in the reciprocal cross. In spite of limited ecotypes tested, these results suggest potential roles of imprinting and NRPD1-mediated small RNA pathway in seed size variation in hybrids.

genetics↗

bioRxiv2023

Protein nonadditive expression and solubility in Arabidopsis hybrids and allotetraploids

Interspecific hybridization in plants often leads to allopolyploids including most important crops such as wheat, cotton, and canola, while many other crops such as corn and sorghum are grown as hybrid. Both allopolyploids and hybrids show hybrid vigor or heterosis. The phenomenon has been widely applied in agriculture and extensively studied at the genetic and gene expression levels. However, proteomic changes in hybrids and polyploids remain poorly understood. Here, we report comparative analysis of soluble and insoluble proteomes in Arabidopsis intraspecific and interspecific hybrids or allotetraploids formed between A. thaliana and A. arenosa. Both allotetraploids and intraspecific hybrids displayed nonadditive expression (unequal to the sum of the two parents) of the proteins, most of which were involved in biotic and abiotic stress responses. In the allotetraploids, homoeolog-expression bias was not observed among all proteins examined but could occur among 17-20% of the nonadditively expressed proteins, consistent with the transcriptome results. Among expression-biased homoeologs, there were more A. thaliana-biased than A. arenosa-biased homoeologs. Analysis of the insoluble and soluble proteomes revealed more soluble proteins in the hybrids than their parents but not in the allotetraploids. Most proteins in ribosomal biosynthesis and in the thylakoid lumen, membrane, and stroma were in the soluble fractions, indicating a role of protein stability in photosynthetic activities for promoting growth. These results collectively support roles of nonadditive expression of stress-responsive proteins and increased solubility of photosynthetic proteins in Arabidopsis hybrids and allotetraploids, which may promote hybrid vigor. Plain Language SummaryWe analyzed fractionated proteomes to test protein abundance and solubility in Arabidopsis hybrids and polyploids. Many proteins in stress-responses are nonadditively expressed in intraspecific hybrids or allotetraploids. There are more soluble proteins of ribosomal biosynthesis and photosynthetic activities in the hybrids than in their parents but not in allotetraploids. Expression levels are equal among most protein homoeologs in the allotetraploids but are biased for ~20% of nonadditively expressed proteins. Nonadditive protein expression and solubility may play a role in heterosis.

genetics↗

bioRxiv2019

A pan-plant protein complex map reveals deep conservation and novel assemblies

Plants are foundational to global ecological and economic systems, yet most plant proteins remain uncharacterized. Protein interaction networks often suggest protein functions and open new avenues to characterize genes and proteins. We therefore systematically determined protein complexes from 13 plant species of scientific and agricultural importance, greatly expanding the known repertoire of stable protein complexes in plants. Using co-fractionation mass spectrometry, we recovered known complexes, confirmed complexes predicted to occur in plants, and identified novel interactions conserved over 1.1 billion years of green plant evolution. Several novel complexes are involved in vernalization and pathogen defense, traits critical to agriculture. We also uncovered plant analogs of animal complexes with distinct molecular assemblies, including a megadalton-scale tRNA multi-synthetase complex. The resulting map offers the first cross-species view of conserved, stable protein assemblies shared across plant cells and provides a mechanistic, biochemical framework for interpreting plant genetics and mutant phenotypes.

systems biology↗

bioRxiv2019

Distinguishing biological from technical sources of variation by leveraging multiple methylation datasets

DNA methylation remains one of the most widely studied epigenetic markers. One of the major challenges in population studies of methylation is the presence of global methylation effects that may mask local signals. Such global effects may be due to either technical effects (e.g., batch effects) or biological effects (e.g., cell-type composition, genetics). Many methods have been developed for the detection of such global effects, typically in the context of epigenome-wide association studies. However, current unsupervised methods do not distinguish between biological and technical effects, resulting in a loss of highly relevant information. Though supervised methods can be used to estimate known biological effects, it remains difficult to identify and estimate unknown biological effects that globally affect the methylome. Here, we propose CONFINED, a reference-free method based on sparse canonical correlation analysis that captures replicable sources of variation--such as age, sex, and cell-type composition--across multiple methylation datasets and distinguishes them from dataset-specific sources of variability (e.g., technical effects). Consequently, we demonstrate through simulated and real data that by leveraging multiple datasets simultaneously, our approach captures several replicable sources of biological variation better than previous reference-free methods and is considerably more robust to technical noise than previous reference-free methods. CONFINED is available as an R package as detailed at https://github.com/cozygene/CONFINED.

bioinformatics↗