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Gu, T.

Publications and source records attributed to Gu, T..

At least 19 recordsLinked to original sources

Biologically Informed Multi-Omics Integration Reveals Clinically Meaningful Patient Representations in Acute Myeloid Leukemia

Integrating heterogeneous molecular and clinical data into unified, clinically meaningful patient representations remains a major challenge in precision medicine. Here, we present SurvMOCA-GNN, a biologically informed multi-omics integration framework that explicitly incorporates biological network structure, cross-omics regulatory relationships, and patient-specific clinical information to generate unified patient representations. Using gene expression, microRNA expression, and clinical data from the TCGA-LAML cohort, SurvMOCA-GNN revealed patient representations that identified prognostically distinct patient groups and further stratified patients within established European LeukemiaNet 2022 risk categories. Systematic ablation analyses demonstrated that incorporation of graph-based modeling, cross-omics attention, adaptive clinical integration, and biological prior knowledge progressively improved integration quality, resulting in more structured patient representations and stronger prognostic stratification. Compared with existing multi-omics integration approaches, SurvMOCA-GNN consistently produced more biologically coherent patient representations with improved survival discrimination. Evaluation in an independent AML cohort, together with transfer learning analyses, further demonstrated the robustness and transferability of the integrated representations across heterogeneous patient populations. Together, these findings demonstrate that biologically informed multi-omics integration reveals clinically meaningful patient representations and provides a general framework for integrating heterogeneous molecular and clinical data to improve patient stratification in AML and potentially other diseases. The SurvMOCA-GNN framework is freely available at https://github.com/tjgu/SurvMOCA-GNN.git.

bioinformatics↗

Single-Cell and Spatial Analysis Reveals Retention of FCRL4⁺ Memory B Cells in Pediatric Tonsillar Hypertrophy

Pediatric tonsillar hypertrophy is a leading cause of sleep disordered breathing in children, yet the immune mechanisms sustaining tonsillar enlargement remain unclear. Using integrated single cell and spatial profiling of pediatric tonsils in a discovery cohort (n = 45) and independent validation cohort (n = 32), we identify a selective expansion and follicular retention of FCRL4+ memory B cells within the mantle zone of hypertrophic tonsils. These cells exhibit a quiescent, tissue-adapted phenotype characterized by NFATC1 repression and reciprocal RUNX1/RUNX2 regulation. Their accumulation is orchestrated by follicular type 1 regulatory T (Tr1) cells, which engage CTLA-4/CD86 checkpoint interactions to suppress plasma cell differentiation and reinforce a local immune tolerance program. Together, these interactions establish a persistent follicular niche enriched in regulatory FCRL4+ memory B cells. Our findings delineate a mechanistic Tr1/FCRL4+ B cell axis underlying follicular hypertrophy and highlight potential immunomodulatory targets for nonsurgical management of pediatric sleep-disordered breathing.

immunology↗

Sex specificity of inhibitory gating deficits in individuals with high autistic traits

Empirical evidence from traditional inhibitory control tasks regarding inhibitory deficits in high autistic traits has been mixed, indicating that this issue remains controversial. Although sex differences are widely documented in autistic cognitive profiles, their role in inhibitory gating mechanisms remains underexplored. Given that the expression of inhibitory gating deficits may be modulated by the social versus non-social nature of stimuli, and no prior study has investigated this topic by integrating both sex differences and stimulus domain, we addressed these two questions with the attribute amnesia paradigm. We manipulated stimulus type (non-social vs. social). In Experiment 1, participants performed a location task with animal drawings as targets and were unexpectedly asked to report animal identity on a surprise trial. High autistic trait females showed significantly higher accuracy on the surprise trial than all other groups, reflecting a failure to actively filter out task-irrelevant non-social information, that is, a reduced inhibitory gating efficiency. In Experiment 2, using face stimuli and a self-vs. other-face design, this gating deficit was no longer expressed: all groups performed at chance levels on the identity judgment, regardless of autistic trait level, sex, or face type. This dissociation aligns with a dual-mechanism framework: the inhibitory gating deficit in high autistic trait females is specific to non-social stimuli and masked by camouflaging for social ones. This study demonstrates that the inhibitory gating deficit in high autistic trait females is not a global impairment but rather a stimulus-dependent one, highlighting the need to consider sex and stimulus type.

neuroscience↗

Human CEBPA-N AML exhibits enhanced engraftment and a C/EBPα-p30-driven leukemic stem cell program

Leukemic stem cells (LSCs) play a central role in disease progression, therapeutic resistance, and relapse in acute myeloid leukemia (AML). However, the identification and characterization of LSCs remain challenging because of their low abundance and their close phenotypic resemblance to normal hematopoietic stem and progenitor cells. Although patient-derived xenograft (PDX) models have provided important insights into AML biology and LSC heterogeneity, the relative engraftment potential of distinct CEBPA mutation subtypes and the immunophenotypic identity of LSCs in CEBPA N-terminal mutant AML (CEBPA-N-AML) remain poorly defined. To address these questions, we compared the engraftment characteristics of primary human CEBPA-mutated AML samples representing the major mutational subtypes using the highly permissive NSGS xenograft model. Primary CEBPA-N-AML samples exhibited markedly greater engraftment efficiency and leukemogenic potential than other CEBPA-mutated AML subtypes. Furthermore, we identified a CD366CD73CD123CD117CD371CD247 cell population that is highly enriched for functional LSCs in CEBPA-N-AML, demonstrating enhanced clonogenic activity, leukemia-initiating capacity, and long-term self-renewal. Collectively, our findings demonstrate that the leukemogenic potential of CEBPA-mutated AML is strongly influenced by mutation subtype, with CEBPA-N-AML exhibiting superior leukemia-propagating capacity in vivo. We further define a novel immunophenotypic LSC signature specific to CEBPA-N-AML, providing new insights into LSC heterogeneity in CEBPA-mutated AML and establishing a foundation for the development of LSC-directed therapeutic strategies.

cancer biology↗

Disease Stage- and Risk-Associated RNA Editing Signatures in Acute Myeloid Leukemia and Their Utility for Peripheral Blood-Based Assessment

RNA editing is a widespread post-transcriptional regulatory mechanism, but its role in acute myeloid leukemia (AML) remains incompletely understood. We analyzed RNA editing in 59 paired diagnosis-relapse AML samples and eight age-matched healthy controls using a stringent discovery pipeline and beta-binomial regression framework accounting for overdispersion and repeated measurements. A total of 166,323 high-confidence RNA editing sites mapping to 5,917 genes were identified. Of tested sites, 1.2%-3.6% varied significantly by disease stage or ELN-2022 risk group. Disease stage-specific editing signatures distinguished healthy controls, diagnosis, and relapse samples, with relapse-associated signals validated in an independent AML cohort. ELN-2022 risk-specific editing signatures showed substantial overlap between intermediate- and adverse-risk groups. Cross-cohort analyses identified four bone marrow (BM) editing sites in TMEM165, COQ4, TIMM17A, and PLXDC2 reproducibly associated with relapse and one peripheral blood (PB) editing site in ABHD18 elevated in higher-risk ELN-2022 groups. Most editing sites were shared between BM and PB; only 2.1%-2.3% exhibited tissue-specific differences. Higher global editing levels were correlated with leukemic state, white blood cell count, and selected clinical features. These findings identify reproducible RNA editing signatures linked to AML disease stage and risk and support the use of RNA editing biomarkers for PB disease assessment.

bioinformatics↗

Evaluating sequence-to-function deep learning models for ancestry-stratified regulatory variant effect prediction using multi-ancestry blood eQTLs

BackgroundSequence-to-function (S2F) deep learning models are increasingly used to prioritize non-coding regulatory variants, but their behavior across ancestrally diverse populations remains unclear. Because both training data and reference resources are heavily European-centered, multi-ancestry benchmarks are needed to determine whether S2F scores capture regulatory effects consistently across populations with different allele-frequency and LD patterns. MethodsWe evaluated Borzoi and AlphaGenome using whole blood eQTL data from the MAGENTA cohort, including African American (AA; N = 224), Caribbean Hispanic (CH; N = 209), and Non-Hispanic White (NHW; N = 235) participants. Model predictions were benchmarked against sampled nominal eQTLs and ancestry-stratified SuSiE fine-mapped variants using Spearman correlation, direction concordance, inter-model convergence, and distance-matched AUROC, with sensitivity analyses for minor allele frequency and comparison-set definition. We also compared FILER functional annotation overlap among high-Posterior Inclusion Probability (PIP) variants across ancestries. ResultsBoth models showed weak agreement with nominal eQTL effect sizes across ancestries and TSS-distance bins ({rho} [&le;] 0.138), with direction concordance only marginally above chance. Agreement and discrimination improved for high-confidence fine-mapped variants, and Borzoi and AlphaGenome showed stronger inter-model convergence on fine-mapped variants than on nominal eQTLs, consistent with enrichment for regulatory variants whose effects are more apparent to sequence-based models. In distance-matched AUROC analyses at PIP [&ge;] 0.9 using PIP < 0.01 variants as low-PIP comparison variants, the AA high-PIP variant set yielded the highest discrimination for both Borzoi (0.837 [95% CI: 0.790-0.870]) and AlphaGenome (0.820 [0.793-0.845]). The CH-versus-NHW ordering was model-dependent: Borzoi yielded higher AUROC in NHW than CH, whereas AlphaGenome produced nearly identical CH and NHW estimates. AUROC values were lower when intermediate-PIP variants were used as comparison variants, but the AA set retained the highest discrimination. MAF-stratified sensitivity analyses attenuated some ancestry contrasts but did not eliminate the higher AA discrimination pattern. Functional annotation analysis showed that AA high-PIP variants more often overlapped chromatin accessibility and chromatin-contact annotations than NHW variants, despite lower overlap with prior eQTL and sQTL annotation catalogs. ConclusionsBorzoi and AlphaGenome showed limited agreement with nominal eQTL effect sizes, but better distinguished high-confidence fine-mapped eQTLs from low-PIP variants. These results support using S2F scores as prioritization evidence for fine-mapped regulatory variants, especially promoter-proximal high-PIP variants, rather than as standalone predictors of eQTL effect size. The strongest discrimination was observed for the AA high-PIP variant set. Overall, the AA result is best interpreted as stronger separation of high-PIP variants from lower-PIP comparison variants, shaped by fine-mapping resolution, LD, the choice of comparison variants, and annotation composition.

bioinformatics↗

Selective encoding failure of self-face identity in subthreshold depression

Subthreshold depression is associated with significant functional impairment and elevated risk of major depressive disorder. A negative self-concept may disrupt the implicit positive association evoked by ones own face, impairing incidental encoding of self-relevant information. Whether subthreshold depression involves a selective deficit in encoding self-face identity remains unclear. The attribute amnesia paradigm is well suited to address this question because it can dissociate attentional selection from working memory encoding. Using this paradigm, we examined the issue across two experiments. Experiment 1 employed nonsocial stimuli (animal drawings) and confirmed an intact attribute amnesia effect in subthreshold depression (n = 30) comparable to healthy controls (n = 30), ruling out a generalized encoding deficit. Experiment 2 replaced targets with faces (self or other) and revealed a selective enhancement of the attribute amnesia effect for self-face identity in subthreshold depression. Specifically, on the surprise trial, accuracy for self-face identity dropped to near-chance levels in the subthreshold depression group, whereas no such deficit emerged for other-faces or in controls. Encoding recovered rapidly once explicit memory expectations were introduced, indicating intact basic encoding capacity. These findings suggest that subthreshold depression is associated with a specific impairment in incidentally encoding self-face identity. This impairment likely stems from a negative self-concept that weakens self-face salience under incidental encoding conditions. By capturing this selective encoding failure, the present study reveals that the self-processing deficit in subthreshold depression can arise at the gating stage between attention and working memory consolidation.

neuroscience↗

Single-cell RNA editing defines clinically relevant cellular states in chronic myelomonocytic leukemia

BackgroundChronic myelomonocytic leukemia (CMML) is a clinically heterogeneous myeloid malignancy with limited therapeutic options and suboptimal risk stratification. Although single-cell RNA sequencing has refined disease classification through gene expression profiling, post-transcriptional mechanisms--particularly adenosine-to-inosine (A-to-I) RNA editing--remain unexplored at single-cell resolution. We hypothesized that cell-specific RNA editing programs contribute to CMML heterogeneity and define distinct, clinically actionable cellular states in CMML. MethodsWe developed a single-cell-aware computational framework for high-confidence identification and quantification of RNA editing events. Candidate sites were detected at pseudo-bulk depth using stringent filters and subsequently quantified at single-cell resolution. The pipeline incorporated dual alignment, barcode correction, artifact removal, and exclusion of genomic variants to ensure specificity. We applied this framework to discovery and independent validation CMML cohorts. Editing-defined cellular states were identified by unsupervised clustering of single-cell editing profiles and evaluated for associations with clinical stage, TET2 status, survival, and response to hypomethylating agent (HMA) therapy. Regulatory mechanisms were assessed by analyzing ADAR1/ADAR2 expression and relationships between editing levels and target gene expression. ResultsWe identified 3,326 high-confidence A-to-I RNA editing sites and delineated reproducible editing-defined cellular states. A granulocyte-monocyte progenitor-like editing state (edClu1_sub0) aligned with an inflammatory, monocytic-biased transcriptional program and was significantly associated with adverse survival, advanced-stage disease and TET2-mutant CMML, supporting it as a high-risk biomarker-defined subpopulation. In contrast, states such as edClu3 and edClu6 were enriched in earlier-stage, TET2-wild-type CMML and correlated with improved outcomes. Editing-defined states demonstrated systematic remodeling following HMA therapy, indicating treatment-responsive post-transcriptional programs. The high-risk state exhibited elevated ADAR1 and reduced ADAR2 expression, suggesting enzyme-specific regulatory imbalance as a potential therapeutic vulnerability. Integrative analyses further nominated immune-related genes--including LAPTM5, CTSS, and CD83--as CMML-specific oncogenic RNA editing targets, with coordinated increases in editing and expression within the aggressive state. ConclusionsRNA editing represents a clinically informative and mechanistically relevant layer that refines CMML stratification at single-cell resolution, independent of gene expression. These findings provide a framework for integrating post-transcriptional regulation into precision oncology and highlight RNA editing signatures as biomarkers for risk assessment, treatment monitoring, and therapeutic targeting in hematologic malignancies.

cancer biology↗

Multiscale RNA editing analysis reveals cell type specific regulatory programs across disease states in acute myeloid leukemia

BackgroundAcute myeloid leukemia (AML) is characterized by marked cellular heterogeneity and immune dysregulation. Adenosine-to-inosine (A-to-I) RNA editing, primarily catalyzed by ADAR and ADARB1, represents an important post-transcriptional regulatory mechanism, yet its condition- and cell type-specific landscape in AML remains poorly defined, particularly at single-cell resolution. MethodsWe analyzed publicly available single-cell RNA sequencing data from healthy donors (HL), newly diagnosed AML (ND), remission (RM), and persistent disease (PO), integrating single-cell and pseudo-bulk analyses in a multiscale framework. RNA editing sites were identified using a stringent discovery pipeline and quantified at both pseudo-bulk and cell type-resolved levels. Differential RNA editing was assessed using regression-based read-count models, primarily beta-binomial regression with subject-specific random effects when applicable. Pairwise contrasts between clinical conditions were evaluated using delta-method inference, with statistical significance defined by false discovery rate and a minimum effect-size threshold. Selected editing sites were examined in independent human AML cohorts for validation and clinical association. ResultsWe identified 2,875 recurrent A-to-I RNA editing sites enriched in intronic and 3' untranslated regions and linked to immune and inflammatory pathways. At the pseudo-bulk level, 150 sites were differentially edited across clinical states, and global RNA editing varied by condition, showing an overall negative association with ADAR and ADARB1 expression with context-dependent exceptions. Cell type-resolved analyses identified 148 differentially edited sites with strong lineage specificity. In ND, leukemia-associated cell states consistently exhibited lower editing than lineage-matched healthy counterparts. T cells consistently harbored differential editing signals across all condition contrasts, while progenitor-like cells showed the strongest RM-versus-ND differences despite minimal changes in global editing. Notable editing events were observed in GBP4, SPN, TNFSF10, EMB, and FKBP5. Several candidate sites were validated in independent AML cohorts and were associated with clinical features. ConclusionsThis multiscale analysis reveals that RNA editing in AML is condition- and cell type-specific and is not fully captured by bulk transcriptomic measures. Site-specific, lineage-restricted RNA editing represents a distinct regulatory layer that reflects disease state and cellular context, highlighting its potential relevance for understanding AML biology and informing future biomarker development.

genomics↗

SurvMarker: An R Package for Identifying Survival-Associated Molecular Features Using PCA-Based Weighted Scores

SummarySurvMarker is an R package for identifying survival-associated features in high-dimensional molecular data using PCA-based weighted scoring. The method aggregates feature loadings across survival-associated principal components (PCs) and evaluates feature significance against a feature-specific empirical null distribution, enabling stable, parsimonious, and statistically calibrated prognostic feature selection. Availability and ImplementationSurvMarker is implemented in R and distributed under the MIT License (MIT). The package includes comprehensive documentation, a reference manual, and a reproducible workflow example, and is provided as Supplementary Material. Source code and documentation are openly available at the GitHub repository https://github.com/tjgu/SurvMarker.

bioinformatics↗

Discovery of miRNA:RNA Biomarkers for Risk Stratification in Acute Myeloid Leukemia with Multi-Cohort Validation

Acute myeloid leukemia (AML) is a clinically aggressive and molecularly heterogeneous malignancy. Current prognostic standards, such as the European LeukemiaNet (ELN) classification, do not fully capture its regulatory complexity. We developed a two-step, PCA-based survival workflow that independently and jointly models gene and miRNA expression to identify biomarkers for patient risk stratification, followed by support vector machine validation across multiple AML cohorts. This strategy enabled rigorous cross-validation while capturing genome-wide regulatory variation. This approach yielded a 19-gene panel--including known oncogenes (e.g., HMGA2, TAL1) and novel candidates (e.g., MLEC, APOE)--that showed robust prognostic performance with validation AUCs>0.879. Parallel analyses identified a 16-miRNA panel enriched for tumor suppressors (e.g., miR-7b-3p, miR-26a-5p) and novel markers (e.g., miR-3613-5p, miR-942-5p), achieving validation AUCs up to 0.916. Integrating experimentally supported miRNA:target interactions revealed 10 coherent regulatory pairs, most showing inverse correlations consistent with miRNA-mediated regulation. Incorporating these regulatory relationships improved prognostic performance compared with single-omic models. Finally, we derived a Cox regression-based molecular risk score that robustly stratified patients and outperformed ELN-2022 risk classification across cohorts. Overall, this framework yields biologically grounded, compact, and reproducible biomarkers with strong prognostic power and provides a generalizable strategy for integrative regulatory modeling in AML.

bioinformatics↗

Multi-ancestry Transcriptome-Wide Association Study Reveals Shared and Population-Specific Genetic Effects in Alzheimer's Disease

Alzheimers disease (AD) risk differs across ancestral populations, yet most genetic studies have focused on non-Hispanic White (NHW) cohorts. We conducted a multi-population transcriptome-wide association study (TWAS) using whole-blood RNA-seq and genotype data from NHW (n=235), African American (AA; n=224), and Hispanic (HISP; n=292) MAGENTA participants. Using SuShiE for multi-population cis-eQTL fine-mapping, we identified credible sets for 8,748 genes, improving fine-mapping precision relative to analyses using fewer populations. cis-eQTL effects were largely shared across populations, with a subset showing population-specific regulation. We performed population-stratified TWAS of AD and inverse variance-weighted meta-analysis, followed by gene-level TWAS fine-mapping (MA-FOCUS), prioritizing nine genes (FDR<0.05, PIP>0.8), including established AD loci (BIN1, PTK2B, DMPK) with broadly consistent effects across populations. At BIN1, fine-mapped cis-eQTL variants used in the TWAS prediction model highlighted rs11682128, which is only modestly correlated with the GWAS index SNP rs6733839 (r2 {approx} 0.34), demonstrating how integrating eQTL fine-mapping with TWAS can refine signals beyond sentinel GWAS variants. We also identified an association between COG4 expression and AD in NHW, implicating Golgi-related pathways. Using independent SuShiE-derived models from TOPMed MESA (PBMC), several signals replicated directionally across ancestries, with the strongest statistical support in NHW. Overall, multi-population eQTL fine-mapping improves model interpretability and helps resolve shared and population-specific regulatory mechanisms relevant to AD.

genomics↗

High-resolution single-cell RNA sequencing using canFam4 reveals novel immune subsets and checkpoint programs in healthy dogs

Single-cell RNA sequencing (scRNA-seq) enables high-resolution profiling of immune heterogeneity. Although previous studies have mapped the single-cell transcriptomic atlases of peripheral leukocytes in healthy dogs, the identification and functional characterization of distinct immune subsets remain incomplete. We constructed a single-cell atlas of peripheral leukocytes from six healthy small-breed dogs using the 10x Genomics platform and the updated canFam4 genome. Analysis of 30,040 high-quality transcriptomes revealed 51 distinct immune subsets, including CD14{square}CD33{square} monocytes, XCR1{square}CD1D{square} dendritic cells, CEACAM1{square}CD24{square} neutrophils, and IL32{square}BATF{square} regulatory T cells, which were underrepresented in canFam3.1-based studies. Interferon-enriched CD14{square} monocytes and CD4{square} T subsets associated with myxomatous mitral valve disease were also identified. Functional analysis revealed that PDCD1 attenuates TCR signaling, LAG3 modulates malate metabolism in CD4{square} T cells, and suppresses TBX21 in CD8{square} T cells associated with viral response. CD274 encoding PD-L1 was linked to IL-10 production in neutrophils, and CTLA4 represented an initial activation of double-negative T subsets. T cell exhaustion scores and proliferative fractions varied across cohorts, reflecting differences in environmental antigenic exposures. Our study represents the first comprehensive, gene-resolved single-cell analysis that reveals immunoregulatory checkpoint mechanisms underlying immune homeostasis in healthy dogs. Our dataset will serve as a valuable resource for future comparative and translational immunology research in dogs.

immunology↗

TSdb: A Curated Database for Terpene Synthases and Their Application in Natural Product Mining

Terpenoids constitute natures most chemically diverse metabolite family with vital pharmaceutical and industrial applications, yet existing databases lack systematic integration of precursor metabolic enzymes (HMGR, DXS) and mechanistic insights into terpene diversification. To bridge this gap, we developed the Terpene Synthase Database (TSDB), distinguishing itself through three key innovations: (1) comprehensive integration of MVA/MEP pathway enzymes with downstream terpenoid synthases, (2) enhanced functional annotation via InterProScan domain mapping and phylogenetics to decode catalytic plasticity, and (3) unprecedented taxonomic breadth spanning 456,142 non-redundant sequences across 30,491 taxa. By consolidating data from BRENDA, UniProt, TeroKit, and ocean gene clusters through rigorous BLASTp deduplication (95% identity cutoff), TSDB reveals 3,499 Gene Ontology terms highlighting core functions like isoprenoid biosynthesis (GO:0019288) and metalloenzyme catalysis. Validation against MIBiG gene clusters (e.g., BGC0001324) demonstrates precise identification of terpene cyclases, P450 monooxygenases, and prenyltransferases with residue-level active site annotations. As the first resource connecting precursor metabolism to structural diversity, TSDB enables accurate gene-enzyme-product prediction for enzyme engineering and natural product discovery.

bioinformatics↗

Heterochromatin-based silencing of a foreign tandem repeat in Drosophila melanogaster shows unusual biochemistry and temperature sensitivity

Eukaryotic genomes are packaged into chromatin, a regulatory nucleoprotein assembly. Establishment, maintenance, and interconversion of chromatin states is required for correct patterns of gene expression, genome integrity, and survival. Transcriptionally repressive heterochromatin minimizes mobilization of transposable elements and limits expansion of other repetitive DNA, but mechanisms for recognition of the latter sequences are not well established. We previously demonstrated in Drosophila melanogaster that transcripts derived from 1360 and Invader4 transposon insertions can trigger local conversion of transcriptionally permissive euchromatin to heterochromatin through the piRNA system, but only in a subset of genomic locations near existing blocks of heterochromatin. Here we show that a ~9 kb tandem array of the 36-nucleotide lac operator (lacO) sequence of Escherichia coli can form ectopic heterochromatin at a similar subset of sites, resulting in variegating expression of an adjacent reporter gene. Heterochromatin Protein 1a (HP1a) and histone deacetylation are required for lacO repeat-induced silencing, but, contrasting with previously described Position Effect Variegation (PEV), we do not observe increased histone H3 lysine 9 methylation. Silencing is effective at 25{degrees}C and suppressed at 18{degrees}C (in contrast to canonical PEV, which is enhanced at 18{degrees}C), indicating involvement of a temperature-sensitive component. Temperature switching experiments show that lacO repeat-induced heterochromatin formation is reversible throughout larval development following an HP1a-dependent initiation step in the early embryo. We conclude that the Drosophila nucleus can recognize a completely foreign tandem repeat as a target for heterochromatin formation, and that the heterochromatin structure established is distinct from that of endogenous tandem arrays.

genetics↗

O-GlcNAcylation-Ubiquitin Crosstalk of METTL1 Drives m7G Epitranscriptomic Collapse and Lipid Metabolic Reprogramming in Diabetic Cardiomyopathy

BackgroundMetabolic remodelling and memory in cardiomyocytes is a pivotal mechanism underlying cardiomyopathy pathogenesis. Clinical observations demonstrate persistent progression of hyperglycaemia-induced multiorgan damage following blood glucose stabilization, which is predominantly mediated through epigenetic regulation. While prior studies have identified epigenetic contributions to hyperglycaemic myocardial injury, the involvement of RNA methylation-particularly N7-methylguanosine (m7G) modification-in this regulatory network remains undefined. MethodsClinical specimens were collected from diabetic patients, and cardiomyocyte-specific METTL1 and ob/ob knockout murine models were established in parallel. Multiomic profiling (proteomics, glycoproteomics, ubiquitinomics, m7G-MeRIP sequencing, and metabolomics) was systematically conducted. The molecular mechanisms governing METTL1 regulation via O-GlcNAcylation and ubiquitination were elucidated through integrated in vitro and in vivo assays. A DUB siRNA library and computational strategies combining molecular docking with molecular dynamics simulations were employed for screening drugs targeting METTL1 O-GlcNAcylation, followed by in vivo therapeutic validation. ResultsComparative analysis of diabetic murine and human samples revealed strong METTL1 downregulation in cardiomyopathy contexts. Tamoxifen-inducible METTL1 knockout mice presented exacerbated diabetic cardiomyopathy phenotypes, confirming its cardioprotective function. Multiomic integration demonstrated that METTL1-mediated m7G modification critically regulates cardiomyocyte fatty acid metabolism. Mechanistically, hyperglycaemia was found to induce O-GlcNAcylation at the METTL1-T268 residue, suppressing m7G methyltransferase activity by 38% (p < 0.01). Subsequent investigations revealed that USP5 deubiquitinase activity is impaired under hyperglycaemic conditions, leading to accelerated METTL1 degradation. Notably, administration of the first-in-class small drug HIT106265621 significantly attenuated cardiomyopathy-associated pathological alterations in ob/ob mice in vivo. ConclusionHyperglycaemia promotes METTL1 O-GlcNAcylation, which impedes USP5-mediated deubiquitination, consequently reducing cardiomyocyte METTL1 protein levels and m7G modification. METTL1 deficiency drives diabetic cardiomyopathy progression through fatty acid metabolic dysregulation, inflammatory activation, and myocardial hypertrophy. Pharmacological inhibition of the OGT-METTL1 interaction using HIT106265621 has therapeutic potential for metabolic cardiomyopathy intervention.

pathology↗

Spleen-derived Small Extracellular Vesicles Protect against Myocardial Infarction via Mediating Spleen-heart Crosstalk

Background and AimsAcute myocardial infarction (AMI) triggers systemic responses that influence cardiac injury and repair, but protective mediators within the cardiosplenic axis remain incompletely understood. This study aimed to investigate whether spleen-derived small extracellular vesicles (sEVs) exert cardioprotection after AMI, identify critical cargo, and evaluate their clinical relevance. MethodsThe effects of splenectomy, spleen-derived sEVs and pharmacological inhibition of sEVs biogenesis on cardiac injury were evaluated in mice with AMI. Parabiosis, donor splenectomy, and fluorescent labelling traced the origin and myocardial recruitment of circulating sEVs. 4D-proteomics profiled sEVs cargo with a focus on pyruvate carrier-1 (MPC1). ResultsSplenectomy worsened survival, ventricular function, infarct size, and fibrosis in mice with AMI. AMI upregulated splenic extracellular-vesicle pathways, with sEVs release peaking at day 3 (M3D-sEVs). Labelled splenic sEVs preferentially accumulated in ischemic myocardium, confirmed by parabiosis experiments. M3D-sEVs improved survival and cardiac function and reduced infarct size, fibrosis, apoptosis, inflammation, and hypertrophy. In addition, anti-apoptotic effects were reproduced in vitro. Inhibition of sEVs biogenesis decreased circulating sEVs, aggravated injury, and was rescued by M3D-sEVs. M3D-sEVs were enriched in MPC1, and MPC1 neutralization or pharmacological blockade abrogated sEVs-mediated restoration of respiration, ATP generation, and reduction of reactive oxygen species. Plasma sEVs-associated MPC1 was highest in patients with AMI, intermediate in coronary heart disease, and lowest in controls. ConclusionsThe spleen responds adaptively to AMI by releasing MPC1lenriched sEVs that travel to injured myocardium, preserve mitochondrial energetics, and reduce damage, supporting cargolspecific sEVs augmentation and sEVslMPC1 as a potential therapeutic target and biomarker in ischemic heart disease. Structured graphical abstractAcute myocardial infarction activates a spleen-heart axis in which the spleen releases mitochondrial pyruvate carrier 1 (MPC1) enriched small extracellular vesicles that home to the infarcted myocardium, preserve mitochondrial oxidative phosphorylation, reduce ROS, and limit infarct size, apoptosis, fibrosis, and hypertrophy. Circulating sEVs-associated MPC1 might serve as a potential biomarker for estimating risk of ischemic heart disease. Translational perspectiveO_LIOur findings reveal a novel heart-spleen communication axis mediated by splenic small extracellular vesicles (sEVs) following AMI. These vesicular messengers predominantly deliver mitochondrial pyruvate carrier 1 (MPC1), enhancing cardiac mitochondrial energy metabolism in the injured myocardium, ultimately improving post-AMI functional recovery in experimental models. C_LIO_LIA higher plasma sEVs-associated MPC1 level was observed in AMI patients when compared with non-AMI patients. These findings support the clinical relevance of the spleen-heart axis, introduce sEVs-associated MPC1 as a potential circulating biomarker for early myocardial injury and therapeutic target. C_LI

molecular biology↗

Rewiring of 3D chromatin topology orchestrates transcriptional reprogramming in muscle fiber-type specification and transformation

The composition of muscle fibers, characterized by distinct contractile and metabolic properties, significantly influences meat quality and glucose homeostasis. However, the mechanisms by which three-dimensional (3D) genome topology integrates with epigenetic states to regulate muscle fiber specification and transformation remain poorly understood. Here, we present an integrative analysis of the transcriptome, epigenome, and 3D genome architecture in the slow-twitch glycolytic extensor digitorum longus (EDL) and fast-twitch oxidative soleus (SOL) muscles. Global remodeling of enhancer-promoter (E-P) interactions emerged as a central driver of transcriptional reprogramming associated with muscle contraction and glucose metabolism. We identified tissue-specific super-enhancers (SEs) that regulate muscle fiber-type specification through cooperation of chromatin looping and transcription factors such as KLF5. Notably, the SE-driven activation of STARD7 facilitated the transformation of glycolytic fibers into oxidative fibers by mitigating reactive oxygen species levels and suppressing ERK MAPK signaling. This study elucidates the principles of 3D genome organization in the epigenetic regulation of muscle fiber specification and transformation, providing a foundation for novel therapeutic strategies targeting metabolic disorders and enhancing meat quality. O_FIG O_LINKSMALLFIG WIDTH=142 HEIGHT=200 SRC="FIGDIR/small/643571v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@990eecorg.highwire.dtl.DTLVardef@a2b491org.highwire.dtl.DTLVardef@1fcd142org.highwire.dtl.DTLVardef@10e4d47_HPS_FORMAT_FIGEXP M_FIG Schematic overview of the study. C_FIG

developmental biology↗