Frontiers in bioscience (Landmark edition)最新文献

Background: Transcription of the hepatitis B virus (HBV) is regulated by the acetylation status of H3/H4 histones bound to the covalently closed circular DNA (cccDNA) minichromosome. Thus, this study aimed to investigate whether sirtuin 7 (SIRT7), an NAD⁺-dependent acetylated lysine 18 of histone H3 (H3K18Ac) deacetylase, represses HBV transcription by catalyzing H3K18 deacetylation on the cccDNA minichromosome.

Methods: We investigated the effects of SIRT7 overexpression/knockdown on HBV transcription and histone acetylation in HepG2.2.15 cells, which constitutively express HBV, and HBV-infected HepG2-NTCP cells. Viral RNA levels and hepatitis B surface and e antigen levels were quantified using reverse transcription quantitative polymerase chain reaction and enzyme-linked immunosorbent assays, respectively. Meanwhile, Western blotting was used to determine protein expression levels. The association between DNA damage-binding protein 1 (DDB1) and cccDNA and the acetylation status of cccDNA minichromosome-associated H3K18 were analyzed using chromatin immunoprecipitation. Co-immunoprecipitation was used to detect protein-protein interactions. Data were statistically analyzed using Student's t-test.

Results: This study demonstrated that SIRT7 enhanced rather than repressed HBV transcription. Mechanistically, SIRT7 promoted HBV transcription by upregulating DDB1, a protein essential for HBV transcription, and by facilitating the recruitment of DDB1 to the cccDNA minichromosome. SIRT7 knockdown inhibited DDB1 expression and reduced DDB1 enrichment on the cccDNA, thereby suppressing HBV transcription. Conversely, SIRT7 overexpression upregulated DDB1 expression and enhanced DDB1-cccDNA binding, eventually promoting HBV transcription.

Conclusions: SIRT7 enhances HBV transcription by upregulating DDB1 expression and promoting an association between DDB1 and cccDNA.

Background: Psoriasis is a chronic inflammatory skin disease driven by an abnormal immune response. Mesenchymal stem cells have strong immunomodulatory properties. Therefore, we investigated the therapeutic effects and underlying mechanisms of human adipose-derived mesenchymal stem cells (hAD-MSCs) in a psoriasis-like mouse model.

Methods: A psoriasis-like mouse model was established and hAD-MSCs were administered via subcutaneous injection. Skin thickness was evaluated using hematoxylin and eosin (H&E) staining, and disease severity was assessed using the Psoriasis Area Severity Index (PASI). Neutrophil counts and Signal Transducer and Activator of Transcription 3 (STAT3) positive keratinocytes in the skin were evaluated by immunohistochemistry (IHC). Additionally, we evaluated the cytokine expression by quantitative PCR (q-PCR).

Results: hAD-MSCs significantly attenuated psoriasis-like skin inflammation. Neutrophil infiltration was markedly reduced in psoriatic lesions following hAD-MSC treatment. We found that hAD-MSCs inhibit neutrophil recruitment by lowering CXCL1 levels in the skin, which may be linked to reduced phosphorylation of STAT3.

Conclusions: Our findings highlight the potential of hAD-MSCs as a potent therapeutic strategy for inhibiting neutrophil recruitment and ameliorating psoriasis-like inflammation.

Background: Vitamin D is essential for skeletal health, but its role in redox homeostasis and cellular senescence during aging in vivo is unclear. We therefore investigated whether active vitamin D insufficiency accelerates bone loss via oxidative stress and senescence pathways.

Methods: Male wild-type (WT) and Cyp27b1 haploinsufficient mice (modeling vitamin D insufficiency) were treated with N-acetylcysteine (NAC) or 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃]. Double-mutant p16^-/-Cyp27b1^+/- mice were used to assess the role of the tumor suppressor protein p16. Mice were maintained until 8 months of age in a specific pathogen-free facility. Outcomes included lifespan (n = variable per group, monitored daily); generation of oxidative stress (determined by serum malondialdehyde [MDA] levels via assay kit); generation of bone reactive oxygen species [ROS] (determined via flow cytometry), development of DNA damage (indicated by 8-hydroxy-2'-deoxyguanosine [8-OHdG] and γ-H2A.X generation and determined via immunohistochemistry and Western blot); and senescence (assessed by generation of β-galactosidase [β-gal], p16, and senescence-associated secretory phenotype [SASP] cytokines as determined via staining, blot, and real-time reverse transcription polymerase chain reaction). Additionally, bone microarchitecture was examined via micro-computed tomography and histomorphometry. Data from at least 5 mice per group were analyzed using unpaired Student's t-test for two-group comparisons and two-way analysis of variance for multi-group comparisons, with significance at p < 0.05.

Results: Compared with wild-type controls, Cyp27b1^+/- mice showed a significantly shorter lifespan, higher oxidative stress, greater DNA damage, increased senescence markers, and lower trabecular bone volume (all p < 0.05). In Cyp27b1^+/- mice, treatment with either N-acetylcysteine or 1,25(OH)₂D₃ significantly improved survival, reduced oxidative stress and DNA damage, attenuated senescence markers, and increased bone volume relative to untreated Cyp27b1^+/- mice (p < 0.05 for all relevant comparisons; n = 5 per group). Genetic deletion of p16 in Cyp27b1^+/-mice similarly increased bone volume and reduced senescence-associated readouts compared with Cyp27b1^+/- controls (p < 0.05; n = 5).

Conclusions: Active vitamin D insufficiency accelerates skeletal aging in vivo through a pathway involving reactive oxygen species-DNA damage-p16/senescence-associated secretory phenotype. Antioxidants, vitamin D repletion, or p16 inhibition rescued bone loss, highlighting redox-senescence axes as potential therapeutic targets for osteoporosis.

Background: Ulcerative colitis (UC) is a chronic inflammatory disorder primarily affecting the rectum and colon. This study aimed to identify potential therapeutic targets that may inhibit UC progression and mitigate patient suffering.

Methods: UC-related datasets were retrieved from the Gene Expression Omnibus database. Differential expression analysis, weighted gene co-expression network analysis, immunoinfiltration analysis, and pyroptosis scoring were employed to identify key pyroptosis-related genes implicated in UC pathogenesis. A dextran sulfate sodium salt (DSS)-induced mouse model of UC was established, and neutrophil extracellular traps (NETs) were induced in neutrophils by stimulation with phorbol 12-myristate 13-acetate (PMA). Histopathological changes in mouse colon tissues were assessed by hematoxylin-eosin staining, and NET formation was evaluated via immunofluorescence. The expression of aquaporin 9 (AQP9), peptidylarginine deiminase 4 (PAD4), zonula occludens 1 (ZO-1), occludin, and proteins related to pyroptosis and the JAK2-STAT3 pathway was determined by Western blotting. Levels of inflammatory cytokines were measured by enzyme-linked immunosorbent assay (ELISA), production of reactive oxygen species was assessed using fluorescent probes, and intestinal epithelial cell viability and death were evaluated using the cell counting kit-8 (CCK-8) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays, respectively.

Results: Five hub genes (AQP9, S100A8, S100A9, S100A12, and VNN2) were identified through bioinformatics analysis, with AQP9 selected for further investigation. Single-cell analysis and immunofluorescence revealed that AQP9 was predominantly expressed in neutrophils and upregulated in the colon tissues of mice with UC and PMA-stimulated neutrophils. Knockdown of AQP9 in PMA-treated neutrophils led to suppression of the JAK2-STAT3 pathway, reduced pyroptosis, and decreased NET formation. Upon co-culture with intestinal epithelial cells, AQP9 knockdown resulted in enhanced epithelial cell viability, reduced apoptosis, and upregulation of ZO-1 and occludin. Conversely, treatment of neutrophils from the PMA+si-AQP9 with a JAK2-STAT3 pathway agonist increased pyroptosis, enhanced the formation of NETs, and induced epithelial cell injury. Similarly, treatment with a pyroptosis agonist enhanced both pyroptosis and the formation of NETs, further aggravating epithelial damage.

Conclusion: Knockdown of AQP9 inhibits JAK2-STAT3 pathway-mediated pyroptosis, thereby reducing the formation of NETs and attenuating intestinal epithelial cell injury.

Tendon-bone healing has always been a difficult point in clinical orthopedics, tissue engineering, and sports medicine. The most important structure for stress transmission is the tendon-bone junction, which is the transition from soft tissue to hard tissue. Biological effects can be produced by a variety of cytokines in different cells. During the remodelling and repair of the tendon-bone junction, the key factor is the inflammatory microenvironment regulated by macrophages through various physiological processes such as autophagy, differentiation, and polarization, which mediate cytokine release and influence other cellular functions. This provides a theoretical basis for the development of new mechanisms for tendon-bone junction repair. This article aims to review the potential role of macrophage autophagy, differentiation, and polarization in the repair of tendon-bone injury. In addition, we propose that future research should integrate multidisciplinary approaches such as molecular biology and bioinformatics to conduct in-depth analyses of the dynamic networks of autophagy and polarization in macrophages, thereby guiding future research directions on the specific roles of macrophage autophagy in tendon-bone junction repair.

Background: The phycobilisomes (PBS) of cyanobacteria and red algae are unique light-harvesting protein-pigment complexes that utilize bilin derivatives for light absorption and energy transfer. These extramembranous mega-Dalton complexes are specifically organized and anchored to photosystem II (PSII) via the multi-domain core-membrane linker (L_CM). While Arm2 is the longest segment in L_CM domain, its specific functions remain uncharacterized.

Methods: A series of Synechocystis sp. PCC 6803 mutants with complete or partial deletions of Arm2 and its adjacent Rep domains within L_CM were constructed. The assembled PBSs were isolatedand characterized using sucrose gradient ultracentrifugation, absorption and fluorescence spectroscopy, and SDS-PAGE. Physiological functions were further assessed by analyzing growth, photosynthetic performance, state transitions, and non-photochemical quenching (NPQ).

Results: Our results reveal that the super-secondary element of helix-turn-helix of Arm2 is critical for assembling the two longitudinal halves of PBS. The truncation of either or both helices of Arm2 results in the specific degradation of the longitudinal half harboring the terminal emitter, ApcD. Consequently, these mutants were deficient in state transitions and exhibited accelerated recovery from orange carotenoid protein (OCP)-mediated NPQ. We also identified the Arm2(37-67) motif likely involved in attaching the rods to the core, whereas the Arm2(68-129) region had no significant impact on PBS assembly.

Conclusions: The helix-loop-helix element of Arm2 is essential for the longitudinal integrity of the PBS core and is a prerequisite for state transitions. These results suggest that state transitions may involve longitudinal rearrangements within the PBS structure, rather than lateral movements of the two halves, implicating that state transitions result from the longitudinal instead of the lateral moves of the two halves of the PBSs.

Background: High-risk neuroblastoma (NB) remains a therapeutic challenge with a poor prognosis, necessitating the identification of novel prognostic biomarkers and effective therapeutics.

Methods: We analyzed transcriptomic datasets from public repositories using weighted gene co-expression network analysis to identify gene modules associated with prognosis. Consensus clustering stratified patients into distinct subgroups. Differential expression analysis, integrated with 80 machine learning algorithm combinations, prioritized hub genes to construct a risk-scoring model, which was implemented via an online platform. We then screened the new drug eugenol using the proximity algorithm and explored its feasibility through in vitro trials.

Results: Consensus clustering based on prognosis-associated modules revealed two patient subgroups with significantly different survival differences (p < 0.001). A set of six hub genes (chromosome 21 open reading frame 58 (C21orf58), cannabinoid receptor 1 (CNR1), laminin alpha 4 (LAMA4), leptin receptor (LEPR), solute carrier family 25 member 10 (SLC25A10), and telomerase reverse transcriptase (TERT)) was identified and used to build a risk-scoring model, accessible at online platform. Leveraging this model, we identified eugenol as a potential therapeutic candidate. Transcriptome analysis showed that eugenol selectively targeted high-risk NB cell populations predicted by the model. Preliminary in vitro experiments investigating its mechanism of action indicated that eugenol primarily functions by inhibiting the MYC-cyclin D1 (CCND1) axis.

Conclusions: This study establishes an integrated precision medicine framework for NB, identifying a new high-risk group and suggesting eugenol as a promising therapeutic candidate for this group, potentially acting through MYC-CCND1 axis suppression.

Tumours contain many fibroblasts, endothelial cells, and leukocytes that are emerging as therapeutic targets complementary to targeting genetically unstable cancer cells. Immunotherapies directed towards this tumour microenvironment (TME) are increasingly effective. Targeting the endothelium has shown success, particularly in hepatocellular carcinoma (HCC). Cancer-associated fibroblasts (CAFs) are also attracting novel nascent therapeutic approaches, and fibroblast activation protein (FAP), which is specific to activated mesenchyme, is prominent amongst CAF markers. This review places emphasis upon FAP, human HCC, and FAP-targeting approaches for therapeutic benefit, including FAP inhibitors, radioligand therapy, T cell and antibody-dependent cytotoxicity/immunotherapy, and FAP-activated prodrugs.

Background: Matrix metalloproteinases (MMPs) are enzymes that degrade extracellular matrix (ECM) proteins and activate cytokines and chemokines, playing a critical role in tissue remodeling. Monitoring MMP activity is important for diagnosing and tracking diseases, studying disease progression, and developing new diagnostic and therapeutic strategies. This article highlights methods for detecting active gelatinases, specifically MMPs-2, -7, -9, and -13 in various biological samples.

Methods: The described protocol utilizes an electrophoresis-based biochemical technique commonly used for protein analysis, with the key modification of incorporating a specific substrate, such as gelatin or casein, into the gel. This method, known as zymography, is named according to the substrate used. For example, it is called 'gelatin zymography' when gelatin is used as the substrate.

Results: When performing zymography, it is crucial to account for the amount of proteinase in different samples, such as plasma which contains significantly higher concentrations of active MMPs compared to other body fluids, tissues, or cells. As a result, only small volumes of plasma are required to produce distinct bands in the zymography gel. Additionally, our findings show that MMP activity, especially active MMP-9, is significantly higher in sonicated samples compared to non-sonicated samples. Therefore, careful consideration of sample preparation, processing, and the amount of protein loading is necessary to achieve high-quality zymography results.

Conclusion: The optimized zymographic protocol presented here enables reliable detection of endopeptidase activities using gelatin or casein as substrates. Other substrates, such as collagen and fibronectin, can also be used to detect collagenase and fibronectinase activities, respectively. This approach facilitates a deeper understanding of metalloproteinase roles in ECM synthesis and degradation, particularly in matrix-related pathologies, including cancer and other tissue disorders. Zymography remains a widely used technique for visualizing ECM protein-degrading enzyme activity in plasma, urine, other body fluids, tissues, and cell culture samples.