Osteosarcoma is a highly heterogeneous and aggressive malignancy with a strong propensity for metastasis, highlighting the need to define its molecular drivers. Here, we report that ASB7 promotes tumor cell protrusion formation, invasion, migration, and lung metastasis. High expression of ASB7 is correlated with a poor prognosis. ASB7 forms an E3 ubiquitin ligase complex with CUL5 to ubiquitinate ATF2 at K383 and promote its proteasomal degradation. ATF2 reduction impairs HDAC6 recruitment to the ITGB2 promoter, thereby alleviating the transcriptional repression of ITGB2. Elevated ITGB2 expression subsequently promotes tumor lung metastasis. Our findings reveal that the ASB7-ATF2/HDAC6-ITGB2 axis regulates osteosarcoma metastasis and suggest potential treatment targets.

BRCA1-deficient epithelial ovarian cancer (EOC) is reported to respond to poly (adenosine diphosphate-ribose) polymerase inhibitors (PARPis); however, acquired resistance frequently emerges, limiting the long-term clinical efficacy of PARPis. The mechanisms driving acquired PARPi resistance in these patients remain poorly understood. In this study, we performed a systemic screen of epigenetic inhibitors in patient-derived organoids (PDOs) and identified enhancer of zeste homolog 2 (EZH2) as the key driver of PARPi resistance in BRCA1-deficient EOC. We found that in PARPi-resistant cells, intracellular EZH2 translocated from the nucleus to the mitochondria, where it promoted mitochondrial fusion and subsequently prevented PARPi-mediated apoptosis. Mechanistically, we determined that PARPi treatment activated YES1 to phosphorylate EZH2 at the Y728 residue, which promoted the mitochondrial translocation of EZH2 in a TOM20-dependent manner. Using mass spectrometry, we identified MYO19 as a main substrate of EZH2 in mitochondria and found that EZH2 trimethylated MYO19 at the K928 residue to trigger mitochondrial fusion. Moreover, Y728 phosphorylation also increased EZH2 protein stability by hindering TRIM4 binding, thus blocking TRIM4-mediated ubiquitination and subsequent proteasomal degradation. Notably, the efficacy of targeting YES1 or EZH2 to resensitize tumors to PARPis was validated in PDOs, xenograft models and EOC cell lines. Here, our findings reveal a YES1-EZH2-MYO19 post-translational modification cascade, whereby PARPi-induced phosphorylation of EZH2 triggered mitochondrial fusion, and targeting phosphorylated EZH2 rebalanced mitochondrial dynamics and resensitized BRCA1-deficient EOC to PARPis, suggesting a promising therapeutic strategy.

SARS-CoV-2 infection has raised significant concerns regarding its impact on assisted reproductive technology. We found that oocyte retrieval during acute SARS-CoV-2 infection significantly reduced the rates of good-quality blastocyst formation, but the underlying molecular mechanisms remain poorly understood. To address this, we investigated the effects of maternal acute SARS-CoV-2 infection on preimplantation embryo development and the early offspring hematopoietic system. Using single-cell RNA sequencing (scRNA-seq), we identified developmental delays in morphologically normal blastocysts from infected mothers, characterized by prolonged expression of zygotic genome activation-related genes, downregulation of mTORC1 signaling, and altered energy metabolism, including suppressed oxidative phosphorylation (OXPHOS) and enhanced glycolysis. We further revealed that maternal acute infection induced abnormal methylation/demethylation patterns in preimplantation embryos. To assess the potential long-term impact on offspring, we conducted integrated multi-tissue analyses, including bulk RNA-seq and genome-wide DNA methylation profiling of placental tissues, along with scRNA-seq of umbilical cord blood (UCB) cells from neonates delivered by SARS-CoV-2-infected mothers. Neonates exhibited elevated levels of inflammatory cytokines and an increased abundance of monocytes, indicating an activated myelopoiesis response. In addition, hematopoietic stem and progenitor cells (HSPCs) from UCB showed reduced OXPHOS activity and a skewed differentiation bias toward the myeloid lineage, potentially impacting long-term immune function. Collectively, these findings reveal that maternal acute SARS-CoV-2 infection impairs preimplantation embryo development and leaves a lasting imprint on offspring hematopoietic health through dysregulated energy metabolism, epigenetic modifications, and altered immune responses.

DNA unwinding and primer synthesis are fundamental processes in genome replication. The human herpes simplex virus type 1 (HSV-1) helicase-primase forms a unique heterotrimeric primosome that is essential for viral DNA unwinding and primer synthesis and represents an ideal drug target. However, its molecular mechanism remains poorly understood. Here we report the cryo-electron microscopic structure of the primosome in complex with single-stranded DNA, ADP and Mg2+ to 3.47 Å resolution, which reveals that the primosome forms an unprecedented architecture in a fully open DNA binding groove between the helicase domains 1A and 2A–2B and that the primase subunit UL52 interacts extensively with the helicase subunit UL5 and accessory protein subunit UL8. Integrating mutagenesis, biochemical assays, structural analysis and 3D variability display analysis, we have identified the active sites of the ATPase, helicase and primase and critical interfaces between UL52, UL5 and UL8. Our work suggests that the primosome unwinds and translocates DNA via bidirectional rotation, and proposes a mechanistic model for DNA-dependent ATPase activation and alternating activity between helicase and primase. Herpesviridae family viruses pose significant threats to human health worldwide, and this trimeric assembly of primosomes is conserved. Our work provides a framework for understanding replication mechanisms across related viruses and for the rational design of broad-spectrum antivirals.

High-efficiency generation of blastoids

Exocrine and endocrine disorders and insufficiency are two major harmful pathological processes in chronic pancreatitis (CP) and can lead to steatorrhea and diabetes. However, there is a lack of reliable clinical classification schemes for evaluating the severity of exocrine and endocrine disorders in CP, and the underlying mechanisms are also unclear. In particular, exosome-based liquid biopsy and classification in CP are lacking. Here, we performed transcriptome sequencing on plasma exosomes from CP patients with different degrees of CP severity. Additionally, we analyzed single-cell sequencing data from pancreatic lesions in CP patients to interpret the classification, and an external cohort was established to verify the classification. Ultimately, we established and preliminarily verified a 3-stage classification system to predict steatorrhea and diabetes onset in CP patients based on the expression of 12 miRNAs in plasma exosomes. A publicly-available online tool implementing this classification system was also developed. Further analysis, in combination with single-cell sequencing data from CP mice, identified exosome-derived miR-24-3p and neutrophil S100A8 as pivotal factors in CP progression. Mechanistically, our findings suggest that downregulated exosome-derived miR-24-3p in CP may lead to the upregulation of its target gene, S100A8, in neutrophils, thus promoting CP-related exocrine and endocrine disorders by activating the fibrotic phenotype of pancreatic stellate cells and inducing inflammation in macrophages, leading to the apoptosis of pancreatic β cells. Together, our work provides a novel exosome-based 3-stage classification system for CP and highlights the role of exosomal miR-24-3p and S100A8 in fibrosis and pancreatic β-cell apoptosis.

Single-domain antibodies (sdAbs) have emerged as powerful therapeutic agents due to their small size, high stability, and superior tissue penetration. However, unlike conventional monoclonal antibodies (mAbs), sdAbs lack an Fc domain, limiting their functional versatility and manufacturability. To address this challenge, we developed TFDesign-sdAb, a deep learning-based generative-ranking framework that enables rational engineering of sdAbs with tailored functionalities. Our framework integrates a structure-aware diffusion model (IgGM) for large-scale candidate generation and a fine-tuned sorter (A2binder) that evaluates and prioritizes them based on predicted functionality. Unlike traditional CDR-focused approaches, TFDesign-sdAb optimizes both complementarity-determining regions (CDRs) and framework regions (FRs), allowing sdAbs to acquire new functional properties while maintaining antigen specificity. We validated our approach by conferring Protein A binding to human VHs and nanobodies that originally lacked this feature, achieving high expression rates, strong binding affinities, and successful purification via industry-standard Protein A affinity chromatography. High-resolution structural characterization (1.49 Å and 2.0 Å) of the redesigned sdAb-Protein A complexes revealed conserved FR-mediated binding motifs that recapitulate natural Fc-Protein A interactions, validating the accuracy of our model. Furthermore, our pipeline streamlined the antibody engineering process, achieving a 100% success rate in generating Protein A-binding sdAbs while maintaining their original antigen-binding affinity. This work demonstrates the power of AI-driven design in overcoming long-standing limitations in antibody engineering and presents a scalable, generalizable solution for enhancing sdAb functionality.