Cell Discovery最新文献

Group 3 innate lymphoid cells (ILC3s) play crucial roles in maintaining intestinal homeostasis and defending against bacterial infections. However, the epigenetic mechanisms that regulate ILC3 responses are not well understood. In this study, we show that Trmt61a, the methyltransferase responsible for the m¹A58 tRNA modification, is predominantly expressed in ILC3s. We found that specific depletion of TRMT61A in ILC3s leads to dysregulated cell cycle and a reduction in cell numbers. Notably, mice with an ILC3-specific TRMT61A deficiency exhibit dysbiosis, but antibiotic treatment can restore colonic ILC3 levels. Furthermore, these mice exhibit increased susceptibility to experimental intestinal inflammation and enteric bacterial infection. Our findings uncover a previously unrecognized role for TRMT61A mediated m¹A modification in the regulation of intestinal ILC3s, essential for protecting intestinal tissue during inflammation and enhancing innate immunity against enteric pathogens.

The remodeling of mammary glands during pregnancy is essential for initiating lactation. In dairy animals, the overlap of pregnancy and mammary involution triggers a unique process, regenerative remodeling, which is critical for extending lactation duration and enhancing milk production. Unlike the complete regression of lobuloalveolar structures during involution, the regenerative remodeling preserves alveolar structures and promotes rapid mammary gland renewal. However, the cellular and molecular mechanisms underlying such process remain elusive. Here, taking dairy goats (Capra hircus) as a ruminant model, we identified four luminal cell populations through single-cell RNA-sequencing and found a significant reduction in luminal hormone-responsive (LumHR) cells and an increase in luminal secretory precursors (LumSecP) during regenerative remodeling. A reduction of LumHR cells during regenerative remodeling is essential for promoting the accumulation of LumSecP. Goat mammary organoids and in vivo genetic ablation assays suggested that LumHR cells function as a crucial switch for the differentiation of LumSecP to LumSec cells through the prolactin receptor pathway. Furthermore, high levels of IRF1 inhibited while downregulation of IRF1 stimulated the proliferation of LumHR cells. We showed that IRF1 regulated the dynamics of LumHR cells through hormonal signaling targets, including ESRRB. Our findings identified a key cell type responsible for the dynamics of luminal lineages during regenerative remodeling in large mammals and highlighted the potential for accelerating tissue regeneration through targeted modulation of lineage stage-specific regulators.

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.

Receptor-like kinases (RLKs) reside on the cell surface and recognize apoplastic colonization by plant-infecting microbes to initiate immune responses. Whether RLKs can also recognize intracellular colonization by viruses to activate antiviral defense mechanisms in plants remains unknown. Here, we report the identification and characterization of a trans-Golgi network/early endosome (TGN/EE)-localized RLK that recognizes viral proteins and inhibits infection in rice. OsVIRK1, a cysteine-rich receptor-like kinase, promotes rice resistance to rice stripe virus (RSV), one of the most devastating viruses of rice. OsVIRK1 transcription is induced in RSV-infected rice, and its protein accumulates through autophosphorylation and redox-mediated regulation. OsVIRK1 physically interacts with the RSV coat protein (CP), a known immune elicitor, and nonstructural protein 3 (NS3), an antiviral RNA-silencing suppressor, at the TGN/EE. OsVIRK1 is required for CP-triggered defense gene expression. It phosphorylates NS3, reducing NS3 accumulation in the cytoplasm and thus repressing its activity as an RNA-silencing suppressor. Our findings suggest that OsVIRK1 recognizes viral proteins at the TGN/EE to inhibit infection by activating plant antiviral immunity and dampening viral counterdefense.

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.

In cancer, extrachromosomal DNA (ecDNA) contributes to tumor heterogeneity and is associated with poor prognosis, but studies on patient-derived ecDNA are relatively limited at single-cell resolution. Here, we introduce scCirclehunter, a framework designed to identify ecDNA from scATAC-seq data and assign ecDNA to specific cell populations. Leveraging scCirclehunter and available glioblastoma (GBM) datasets, we uncover the inter-cellular heterogeneity of ecDNA-carrying cells across GBM patients and trace the trajectories of malignant cells within a single patient that harbors multiple ecDNAs. By integrating scRNA-seq data, we use ecNR2E1 as an example to demonstrate that ecDNA drives tumor progression in GBM through several mechanisms. Additionally, our findings suggest a potential link between ecDNA and increased mitochondrial transfer frequency. Overall, scCirclehunter provides a novel framework for analyzing patient-specific ecDNAs with single-cell precision, offering insights into the role of ecDNA-carrying cells in driving GBM heterogeneity.

Protease-activated receptor 2 (PAR2) is a transmembrane receptor that is irreversibly activated by proteolytic cleavage of its N-terminus via extracellular proteases, resulting in the release of the tethered ligand (TL), which binds to and activates the receptor. PAR2 plays a pivotal role in the inflammatory response and pain sensation and is a promising drug target for treating arthritis, asthma, and neuronal pain. Here, we present the cryo-electron microscopy structures of active PAR2 complexed with miniG_s/q and miniG₁₃. Combining functional assays with structural analysis, our study revealed that TL forms a parallel β-sheet with the extracellular loop 2 of PAR2 to engage the receptor. The binding of TL triggers a conformational rearrangement in the transmembrane core, releasing the inhibitory ion lock and allowing receptor activation. Furthermore, we provide structural insights into the engagement of G_q and G₁₃ with PAR2, highlighting that a hydrophobic interaction mediated by the last methionine residue of Gα₁₃ is crucial for G₁₃ coupling selectivity. In combination with molecular dynamics simulations and mutagenesis, we identified the I39^TL3/D62^N-term interaction at the pocket side of the receptor as a key determinant of G₁₃ signaling. Disrupting this interaction significantly inhibits G₁₃ signaling while preserving G_q activity, enabling us to design a biased peptide ligand that selectively activates G_q signaling. The information revealed in this study provides a framework for understanding PAR2 signaling and offers a rational basis for the design of biased PAR2 ligands.