Genes to Cells最新文献

The thymidine analog EdU (5-ethynyl-2-deoxyuridine) is incorporated into DNA during replication and has traditionally been used as a marker of S-phase cells. In this study, we discovered that EdU fluorescence images display substantial cell-to-cell variability, which could be classified into multiple clusters by unsupervised machine learning. This suggests that seemingly random EdU patterns contain reproducible, computationally recognizable features. Building on our observation that distinct patterns emerged in response to radiation stress, we investigated whether radioresistant cancer cells exhibit specific EdU signatures. Analysis of PLK1-overexpressing cells, which acquire radioresistance through altered DNA replication, revealed radiation-induced EdU patterns distinct from control cells. Prompted by the observation that these cells displayed markedly enlarged and intensified γ-H2AX foci, a marker of DNA damage, we employed a supervised machine learning model based on γ-H2AX patterns to isolate the radioresistant cell subpopulation. We then extracted the EdU signals from these isolated cells and, through further unsupervised machine learning, successfully identified a characteristic pattern specific to radioresistance. This establishes a machine learning framework capable of extracting universal rules from the dynamic networks that vary among individual cells, which provides a novel platform for a screening system to identify molecules involved in radioresistance, focusing on cancer heterogeneity.

Peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear receptor abundantly expressed in the fatty liver of type 2 diabetic ob/ob mice. Herein, we investigated how PPARγ regulates the expression of the interferon alpha-inducible protein 27-like 2b (lfi27l2b) gene in the mouse liver. High expression of lfi27l2b was observed in the fatty liver of ob/ob mice, and the expression was further upregulated by PPARγ ligands; however, liver-specific Pparg knockout ameliorated this increase. Moreover, high lfi27l2b expression was observed in the fatty liver of alcohol-fed mice. Reporter assays indicated that the PPARγ-responsive element (PPRE) is necessary for PPARγ-dependent induction of Ifi27l2b promoter activities. Furthermore, electrophoretic mobility shift assays showed that PPARγ is capable of directly binding the PPRE. Overall, our results indicate that lfi27l2b is a novel PPARγ target in the fatty liver.

Staphylococcus aureus (S. aureus) produces various bicomponent pore-forming toxins (PFTs), including the γ-hemolysins (HlgAB and HlgCB) and leukocidins (LukAB and LukED). This study aimed to examine the effect of PFTs on murine bone marrow-derived mast cells (BMMCs). All the PFTs assessed in this study (HlgAB, HlgCB, LukAB, and LukED) were found to bind to BMMCs. Specifically, HlgAB and LukED, but not HlgCB or LukAB, induced membrane damage. Furthermore, only HlgAB induced BMMC degranulation, whereas HlgAB and HlgCB significantly augmented the degranulation caused by ionophore, immunocomplex, and staphylococcal δ-toxin. The augmentation of degranulation by HlgAB was impaired when a pore-formation defect mutant of HlgB (HlgBΔstem) was used. Conversely, the augmentation by HlgCB was unaffected following the use of HlgBΔstem, suggesting that HlgAB but not HlgCB augments degranulation in a pore-formation-dependent manner. These results highlight the novel roles for the staphylococcal γ-hemolysins HlgAB and HlgCB, as they differentially affect the degranulation of mast cells in the effector phase of allergic inflammation.

The mid-oogenesis checkpoint in Drosophila melanogaster functions to optimize nutrient usage by triggering abortion of oogenesis when females are starved or when developmental defects arise in the egg chamber. In the Dyro mutant, which encodes a nuclear factor, oogenesis is aborted during stages 8–9, corresponding to the mid-oogenesis checkpoint. To investigate the relationship between Dyro and this checkpoint, we analyzed the phenotype of the Dyro mutant. Mosaic analysis showed that loss of Dyro in germline cells results in female sterility. Although inhibition of programmed cell death suppressed germline cell death during oogenesis, it failed to rescue the fertility of Dyro mutants, suggesting that oogenesis arrest in the Dyro mutant is not due to misregulation of the cell death signal. We then examined germline cell defects in the Dyro mutant and observed morphological abnormalities in the nucleoli and chromosomes of nurse cells. The chromosomes in Dyro mutant nurse cells were not fully dispersed, and the nucleoli were confined to small spaces between thickened chromosomes. These findings suggest that Dyro plays an important role in nurse cells and that loss of Dyro leads to defects in the chromosomes and nuclei of nurse cells, which leads to abortion of oogenesis.

This study investigates the maturation status of rat lung epithelial cells in interspecies chimeras generated via blastocyst complementation (BC) using Fgfr2b-knockout mouse embryos. In our previous study, we succeeded in generating rat-derived lung epithelium in interspecies chimeras using tetraploid complementation; however, the resulting cells remained immature and failed to support respiratory function. In this study, we established two Fgfr2b-KO mouse lines via CRISPR/Cas9 and injected GFP-labeled rat embryonic stem (ES) cells into blastocysts, which were then transferred to pseudopregnant female mice. Comparative histological analysis of airway spaces between wild-type rat lungs (E19.5–E21.5) and BC chimeras revealed that BC lungs reached a maturation stage comparable to E20.5–E21.5 rat lungs. Quantitative Polymerase Chain Reaction of key epithelial maturation markers—including ENaC subunits, Aqp5, and surfactant protein genes—demonstrated late-gestational upregulation in wild-type rat lungs, while expression levels in BC lungs exhibited significant inter-individual variability, corresponding to stages between E19.5 and E21.5 in wild-type rats. These findings suggest that the mouse host environment may partially promote maturation of rat-derived lung epithelial cells; however, additional mechanisms are likely required to achieve functional respiratory capacity.

The fifth international meeting, entitled “SMC Complexes: Orchestrating Diverse Genome Functions”, took place in Numazu City, Shizuoka, Japan from October 15–18, 2024. With 159 attendees (115 of whom were from 18 countries and regions), the meeting aimed to further our understanding of large-scale chromosome organization and related chromosomal events, which are mediated by SMC complexes, one of the major architects of chromosomes. Discussion at the meeting was prompted by 49 talks and 82 poster presentations, which covered a variety of topics including the eukaryotic cohesin, condensin and SMC5/6 complexes, as well as bacterial and archaeal SMC complexes. Various cutting-edge approaches, ranging from molecular dynamics simulations to medical genetics, were developed and applied to reveal the functions of SMC complexes at mechanical and chromosomal levels. All attendees enjoyed the presentations of leading works and discussions with leading scientists in the field of chromosome biology.