摘要: In the meiotic prophase, programmed SPO11-linked DNA double-strand breaks (DSBs) are repaired by homologous recombination (HR). The MRE11-RAD50-NBS1 (MRN) complex is essential for initiating DNA end resection, the first step of HR. However, residual DNA end resection still occurs in Nbs1 knockout (KO) spermatocytes for unknown reasons. Here, we show that DNA end resection is completely abolished in Mre11 KO spermatocytes. In addition, Mre11 KO, but not Nbs1 KO, undifferentiated spermatogonia are rapidly exhausted due to DSB accumulation, proliferation defects, and elevated apoptosis. Cellular studies reveal that a small amount of MRE11 retained in the nucleus of Nbs1 KO cells likely underlies the differences between Mre11 and Nbs1 KO cells. Taken together, our study not only demonstrates an irreplaceable role of the MRE11 in DNA end resection at SPO11-linked DSBs but also unveils a unique function of MRE11 in maintaining the long-term viability of undifferentiated spermatogonia.

摘要: Chimeric antigen receptor-natural killer (CAR-NK) cell therapy is emerging as a promising cancer treatment, with notable safety and source diversity benefits over CAR-T cells. This study focused on optimizing CAR constructs for NK cells to maximize their therapeutic potential. We designed seven CD19 CAR constructs and expressed them in NK cells using a retroviral system, assessing their tumour-killing efficacy and persistence. Results showed all constructs enhanced tumour-killing and prolonged survival in tumour-bearing mice. In particular, CAR1 (CD8 TMD-CD3 zeta SD)-NK cells showed superior efficacy in treating tumour-bearing animals and exhibited enhanced persistence when combined with OX40 co-stimulatory domain. Of note, CAR1-NK cells were most effective at lower effector-to-target ratios, while CAR4 (CD8 TMD-OX40 CD- Fc epsilon RI gamma SD) compromised NK cell expansion ability. Superior survival rates were noted in mice treated with CAR1-, CAR2 (CD8 TMD- Fc epsilon RI gamma SD)-, CAR3 (CD8 TMD-OX40 CD- CD3 zeta SD)- and CAR4-NK cells over those treated with CAR5 (CD28 TMD- Fc epsilon RI gamma SD)-, CAR6 (CD8 TMD-4-1BB CD-CD3 zeta 1-ITAM SD)- and CAR7 (CD8 TMD-OX40 CD-CD3 zeta 1-ITAM SD)-NK cells, with CAR5-NK cells showing the weakest anti-tumour activity. Increased expression of exhaustion markers, especially in CAR7-NK cells, suggests that combining CAR-NK cells with immune checkpoint inhibitors might improve anti-tumour outcomes. These findings provide crucial insights for developing CAR-NK cell products for clinical applications.

摘要: Macrophage pyroptosis is of key importance to host defence against pathogen infections and may participate in the progression and recovery of periodontitis. However, the role of pyroptotic macrophages in regulating periodontal ligament stem cells (PDLSCs), the main cell source for periodontium renewal, remains unclear. First, we found that macrophage pyroptosis were enriched in gingiva tissues from periodontitis patients compared with those of healthy people through immunofluorescence. Then the effects of pyroptotic macrophages on the PDLSC osteogenic differentiation were investigated in a conditioned medium (CM)-based coculture system in vitro. CM derived from pyroptotic macrophages inhibited the osteogenic differentiation-related gene and protein levels, ALP activity and mineralized nodule formation of PDLSCs. The osteogenic inhibition of CM was alleviated when pyroptosis was inhibited by VX765. Further, untargeted metabolomics showed that glutamate limitation may be the underlying mechanism. However, exogenous glutamate supplementation aggravated the CM-inhibited osteogenic differentiation of PDLSCs. Moreover, CM increased extracellular glutamate and decreased intracellular glutamate levels of PDLSCs, and enhanced the gene and protein expression levels of system xc- (a cystine/glutamate antiporter). After adding cystine to CM-based incubation, the compromised osteogenic potency of PDLSCs was rescued. Our data suggest that macrophage pyroptosis is related to the inflammatory lesions of periodontitis. Either pharmacological inhibition of macrophage pyroptosis or nutritional supplements to PDLSCs, can rescue the compromised osteogenic potency caused by pyroptotic macrophages. This study revealed that glutamate metabolism plays an important role in the macrophage pyroptosis-compromised periodontal ligament stem cell osteogenic differentiation. In contrast to previous strategies to change the stem cell fates, such as gene therapy, supplementation with nutrients such as cystine can also improve the performance of stem cells in inflammatory microenvironment. image

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摘要: Alternative splicing (AS) disruption has been linked to disorders of muscle development, as well as muscular atrophy. However, the precise changes in AS patterns that occur during myogenesis are not well understood. Here, we employed isoform long-reads RNA-seq (Iso-seq) and single-cell RNA-seq (scRNA-seq) to investigate the AS landscape during myogenesis. Our Iso-seq data identified 61,146 full-length isoforms representing 11,682 expressed genes, of which over 52% were novel. We identified 38,022 AS events, with most of these events altering coding sequences and exhibiting stage-specific splicing patterns. We identified AS dynamics in different types of muscle cells through scRNA-seq analysis, revealing genes essential for the contractile muscle system and cytoskeleton that undergo differential splicing across cell types. Gene-splicing analysis demonstrated that AS acts as a regulator, independent of changes in overall gene expression. Two isoforms of splicing factor TRA2B play distinct roles in myogenic differentiation by triggering AS of TGFBR2 to regulate canonical TGF-beta signalling cascades differently. Our study provides a valuable transcriptome resource for myogenesis and reveals the complexity of AS and its regulation during myogenesis.

摘要: Neutrophil extracellular trap (NET) has been confirmed to be related to gut barrier injury during intestinal ischaemia-reperfusion (II/R). However, the specific molecular regulatory mechanism of NETs in II/R-induced intestinal barrier damage has yet to be fully elucidated. Here, we reported increased NETs infiltration accompanied by elevated inflammatory cytokines, cellular necroptosis and tight junction disruption in the intestine of human II/R patients. Meanwhile, NETs aggravated Caco-2 intestinal epithelial cell necroptosis, impairing the monolayer barrier in vitro. Moreover, Pad4-deficient mice were used further to validate the role of NETs in II/R-induced intestinal injury. In contrast, NET inhibition via Pad4 deficiency alleviated intestinal inflammation, attenuated cellular necroptosis, improved intestinal permeability, and enhanced tight junction protein expression. Notably, NETs prevented FUN14 domain-containing 1 (FUNDC1)-required mitophagy activation in intestinal epithelial cells, and stimulating mitophagy attenuated NET-associated mitochondrial dysfunction, cellular necroptosis, and intestinal damage. Mechanistically, silencing Toll-like receptor 4 (TLR4) or receptor-interacting protein kinase 3 (RIPK3) via shRNA relieved mitophagy limitation, restored mitochondrial function and reduced NET-induced necroptosis in Caco-2 cells, whereas this protective effect was reversed by TLR4 or RIPK3 overexpression. The regulation of TLR4/RIPK3/FUNDC1-required mitophagy by NETs can potentially induce intestinal epithelium necroptosis.

摘要: With the continuous increase of the elderly population and the deepening of population ageing in China, osteoporosis has gradually become one of the significant public health problems. Elucidating the pathophysiological mechanisms that induce osteoporosis and identifying more effective therapeutic targets is of great clinical significance. In this study, in vitro experiments demonstrated that endothelial cell exosomes (EC-EXOs) promoted osteogenic and inhibited adipogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Aged and ovariectomy (OVX)-induced osteoporosis mice models injected with EC-EXOs confirmed that EC-EXOs delayed bone loss. Proteomic analysis revealed a key protein regulating the differentiation of BMSCs. Expression of THBS3 was significantly higher in EC-EXOs than in Human microvascular endothelial cells (HMEC-1). In vitro and in vivo experiments further validated that THBS3 promoted BMSCs' osteogenic differentiation, inhibited their adipogenic differentiation, and retarded bone loss. Computational biology analysis found that CD47 is a downstream target and potentially functional receptor in BMSCs that bind to THBS3. THBS3 treatment of BMSCs down-regulated the expression of CD47 in in vitro experiments. The aged/OVX models further confirmed that EC-EXOs can regulate the differentiation of BMSCs and delay the process of bone loss via the THBS3-CD47 axis. CD47 antibody may be a potential therapeutic agent for treating ageing-associated bone loss.

摘要: This paper discussed the role of AlkB homologue 5 (Alkbh5) in the progression of lipopolysaccharide (LPS)-induced acute lung injury (ALI). LPS-induced ALI models were established in Alkbh5 knockout (KO) and knock-in (KI) mice. The m6A levels in lung tissues were analysed using m6A dot assays. The lung injury was analysed by determining ALI-related markers and histological staining. Mouse MLE12 cells were exposed to LPS for in vitro experiments, and the influence of Alkbh5 on cell viability, apoptosis and reactive oxygen species (ROS) production was analysed. RNA-seq analysis was performed to analyse gene changes upon Alkbh5 deficiency. Functions of the Alkbh5-C-C motif chemokine ligand 1 (Ccl1) cascade in ALI were further verified using the Alkbh5 antagonist DDO-2728 and a recombinant protein of Ccl1 (mCcl1). Alkbh5 was upregulated in lung tissues following LPS exposure. Alkbh5 knockout in mice mitigated LPS-induced lung injury, as indicated by reduced serum levels of lung injury markers and reduced immune cell infiltration, fibrosis and apoptosis. Conversely, Alkbh5 overexpression in mice resulted in reverse trends. In vitro, Alkbh5 knockdown in MLE12 cells enhanced cell viability while reducing cell apoptosis and ROS production. Mechanistically, Alkbh5 was found to bind to and destabilise Ccl1 mRNA, leading to increased Treg recruitment. Treatment with DDO-2728 or mCcl1 in mice increased Treg infiltration, thus improving lung tissue pathology and reducing lung injury. This study suggests that Alkbh5 is implicated in ALI progression by reducing Ccl1-mediated Treg recruitment, making it a promising target for ALI management.

摘要: Uterine fibroids (UFs) are the most common benign gynecologic tumours affecting women of reproductive age. This study aims to deepen the understanding of UFs complex aetiology through harnessing the power of 3D organoid models derived from human myometrial stem cells to emulate the in vivo behaviour of these tumours. Isolated SCs were cultured over 7 days under a defined culture system. Immunohistochemistry, Immunofluorescence, organoid stiffness, RNA Sequencing was conducted, and differential gene expression was assessed using RT-PCR. The derived organoids exhibited diverse populations of cells, including stem cells, smooth muscle, and fibroblasts. Excessive ECM deposition was shown via Collagen and Fibronectin expression. We confirmed that our organoids expressed oestrogen receptor in a pattern similar to that in their corresponding tissue, as well as responded to steroid hormone. Interestingly, we revealed significant racial disparities in ECM accumulation within organoids derived from different racial groups. This augmented ECM deposition is theorised to enhance tissue stiffness, as assessed using Young's modulus. Additionally, our research demonstrated significant decreases in fibrotic markers upon treatment with Vitamin D3 and Doxercalciferol. Furthermore, the pro-fibroid effects of environmental phthalates further elucidate the potential factors contributing to UF pathology. The 3D organoid model can serve as a robust platform to study the underlying molecular mechanisms of UFs, besides offering invaluable insights for potential therapeutic interventions.