Inteins are unique protein insertion sequences capable of self-excision, enabling the covalent ligation of flanking extein peptides via amide bond formation. This process proceeds spontaneously without requiring external enzymes, cofactors, or chemical reagents, granting inteins exceptional biocompatibility and traceless performance in protein engineering applications. Split inteins represent a specialized and versatile subclass whose splicing domains are encoded by two separate gene fragments rather than a single continuous open reading frame. These fragments, known as the N-terminal (IntN) and C-terminal (IntC) split inteins, associate through non-covalent interactions including hydrophobic forces, hydrogen bonds, and van der Waals forces to assemble into an active three-dimensional structure, which then drives efficient extein ligation and enables protein trans-splicing. Protein trans-splicing mediated by split inteins has become a cornerstone for traceless protein ligation owing to its high specificity and irreversibility, fundamentally reshaping strategies for protein modification, assembly, and functional regulation. Compared with traditional chemical ligation methods, split intein systems require no complex chemical derivatization of peptide fragments and can operate efficiently at micromolar concentrations under physiological conditions, thus avoiding structural and functional damage caused by organic reagents. In contrast to enzymatic ligation tools such as sortase, split inteins eliminate the need for additional enzymes or cofactors, simplifying reaction systems, reducing costs, and minimizing non-specific side products. These distinctive advantages render split inteins highly promising for applications in chemical biology, synthetic biology, and biopharmaceutical development. In recent years, deepened mechanistic understanding has established structure-guided rational design as the primary approach to overcoming key limitations of split inteins, including intrinsic aggregation propensity, strict extein sequence dependence, and limited splicing efficiency. Bioinformatic tools have been used to identify aggregation-prone regions in the IntN fragment, and site-directed mutagenesis of hydrophobic residues, relocation of split sites, or removal of misfolding-prone sequences has substantially reduced in vitro aggregation and improved soluble expression and assembly activity. Rational engineering of catalytic residues and adjacent flexible loops has relaxed strict amino acid preferences at extein junctions, enhancing sequence tolerance and reducing the risk of functional impairment in target proteins. Consensus design based on multiple sequence alignments has yielded ultra-fast splicing variants such as Cfa DnaE and Cat-TerL, which exhibit significantly accelerated kinetics and improved tolerance to denaturing conditions. Meanwhile, advances in structural biology have further clarified the conformational dynamics and catalytic mechanisms of splicing, supporting the precise design of high-performance intein modules. On this basis, electrostatic interaction tuning and metagenomic screening have yielded multiple mutually orthogonal split intein pairs, enabling selective multi-fragment protein ligation and providing new routes for the efficient synthesis of large multi-domain functional proteins. With these engineered split inteins offering continuously improved performance and expanded applicability, protein trans-splicing has been widely applied in numerous cutting-edge areas of protein research and biomedicine. In gene delivery, split intein-based systems overcome the packaging limit of adeno-associated viral vectors, enabling the accurate reconstitution of large therapeutic proteins and base editors in target cells, thereby enhancing the efficacy and scope of gene therapy for genetic diseases. In internal protein sequence editing, split inteins mediate precise sequence replacement and modification in flexible regions or loops of target proteins, without the need for complex multi-step ligation and protein refolding involved in traditional protein semisynthesis. In protein-protein interaction studies, intein-mediated splicing covalently captures transient and weak intracellular complexes, enabling sensitive, high-throughput interaction detection and drug screening. In synthetic biology, conditionally controllable splicing systems support the construction of diverse intracellular and cell-surface biological logic gates for the precise regulation of cellular behavior. In mechanistic biochemical research, split inteins enable photocatalytic proximity labeling and site-specific tagging, allowing the preparation of homogeneous protein samples carrying precise post-translational modifications such as ubiquitination and polyglutamylation for chromatin interactome analysis and epigenetic studies. Moreover, covalent trapping strategies using split inteins stabilize transient enzymatic intermediates, providing unprecedented insights into molecular mechanisms such as nucleosome ubiquitination that are difficult to elucidate using conventional methods. This review systematically summarizes key technological advances in split inteins over the past decade, highlighting engineering strategies, mechanistic insights, and the development of orthogonal components. It comprehensively surveys emerging applications at the frontiers of protein research, analyzes current core challenges, and proposes future directions, particularly emphasizing artificial intelligence-driven de novo design and novel splicing pathways to break existing technical bottlenecks. By enabling traceless, efficient, and versatile protein manipulation, split inteins continue to serve as indispensable tools that drive innovation in protein engineering and fundamental life science research.

ObjectiveThis study aimed to elucidate the mechanistic role of Staphylococcus aureus in the pathogenesis of atopic dermatitis (AD), a chronic inflammatory skin disorder characterized by pruritus and barrier dysfunction. A key focus was screening traditional Chinese medicine (TCM) active components with dual antibacterial and antipruritic efficacy, followed by systematic evaluation of their in vitro antibacterial activity. Additionally, a novel drug delivery system was constructed to enable localized efficient drug delivery, inhibiting S. aureus proliferation and alleviating its induced pruritus, thereby providing new strategies for targeted AD therapy. MethodsMale C57BL/6J mice aged 6-8 weeks (body weight 18-22 g) were used to establish an AD model via repeated oxazolone sensitization. On day 14, microbial samples were collected from the lesional area (1 cm²) using sterile cotton swabs, followed by vortex mixing, serial dilution, and plating on 5% sheep blood agar plates (incubated at 37°C for 24 h). Single colonies with complete transparent β-hemolytic zones were isolated and identified as vancomycin-intermediate S. aureus (VISA) via 16S rRNA sequencing. An S. aureus mono-infection animal model was then established by applying gauze saturated with bacterial suspension (McFarland turbidity 0.1) to the nape and back skin of mice. The pruritic phenotype and inflammatory cell infiltration induced by S. aureus were evaluated using comprehensive approaches including behavioral assays (e.g., scratching frequency recording), hematoxylin-eosin (HE) staining, and toluidine blue staining. The in vitro antibacterial efficacy of the TCM monomer pseudolaric acid B (PAB) and double network hydrogel (DN) was separately assessed by disk diffusion assay, while the minimum inhibitory concentration (MIC) of PAB was determined via broth dilution method. Further validation of the pharmacodynamic characteristics of the composite system (PAB@DN, composed of PAB and DN) was conducted through behavioral assays, HE staining, and dermatitis scoring, with its drug release profile evaluated by mass spectrometry analysis. Based on scratching behavioral analysis and dermatitis scoring, the optimal ratio and concentration of PAB@DN were optimized. ResultsThe S. aureus load in AD lesional tissues was significantly higher than in normal skin ((5.3±0.33)×10⁶ CFU vs. (3.6±0.26)×10⁷ CFU, P<0.001). In the S. aureus mono-infection group, mice exhibited a 6.7-fold increase in scratching frequency compared to the control group. HE staining revealed marked epidermal thickening ((10.4±2.39) μm vs. (85.6±1.95) μm, P<0.000 1), and toluidine blue staining showed a 23-fold increase in mast cell degranulation. Pseudolaric acid B exhibited a significant concentration-dependent inhibitory effect onS. aureus growth, with its in vitro antibacterial effect being 57% that of the antibiotic cefepime (inhibition zone diameter: PAB (1.885±0.036) cm vs. cefepime (3.636±0.005) cm, P<0.000 1) and a minimum inhibitory concentration (MIC) of 1 g/L. The carrier double network hydrogel (DN) itself lacked direct antibacterial activity (no significant difference in inhibition zone diameter compared to the control) but effectively ameliorated the dry symptoms of AD-like lesions. The PAB@DN composite system demonstrated a synergistic effect compared to individual components, resulting in a 50% reduction in scratching behavior, an 86% decrease in dermatitis score, and a 60% reduction in epidermal thickening. It also reduced the S. aureus load in mouse skin by approximately 34%, with the optimal effective formulation being PAB at 1 g/L loaded onto DN. ConclusionS. aureus colonization plays a critical driving role in the onset and progression of AD. Using an S. aureus infection model, this study confirmed that the pseudolaric acidB-hydrogel composite delivery system (PAB@DN) can effectively alleviate S. aureus-induced pruritus and skin damage, providing experimental evidence for microbiota-targeted therapy of AD.

Objective This study reports on the obligatory parasitism of water mites Arrenurus sp. on Anopheles messeae at the Manzhouli Port, Inner Mongolia, China. Methods Duing July 2024, a survey on the mosquito diversity was conducted at the Manzhouli Port. Captured mosquitoes and their ectoparasites were identified to species level. Results A total of 1840 adult mosquitoes were collected, representing species from three genera: Culex(Cx. modestus, Cx. pipiens pallens), Aedes(Ae. dorsalis, Ae. flavidorsalis, Ae. flavescens), and Anopheles (An. messeae). Among all the mosqutioes specimens,3 out of 150 captured An. messeae were found to carry ectoparasitic mites, with number of 2,4,27 mites separately. Morphological and molecular identification reached the same result as water mites(Hydrachnidiae, Hydracrina). COI gene sequence showed 94% similarity with the closest species Arrenurus truncatellus. Conlusions Literature review suggests water mites are host-specific parasitism of mosquito species and herein with the first record of Arrenurus sp. parasiting on An. Messeae in the most high-latitude region globally.

To construct a recombinant fowl adenovirus 4(FAdV-4)expressing the Cap protein of goose astrovirus genotype 2(GoAstV-2),the expression cassette of Cap gene was inserted into the natural 1 966 bp deletion region of the FAdV-4 genome in the infectious clone p15A-cm-FAdV4-HNJZ.The resulted recombinant plasmid p15A-cm-FAdV4-HNJZ-Cap/GoAstV-2 was linearized with restriction enzyme and transfected into chicken hepatoma cell line(LMH)to rescue the recombinant FAdV-4 expressing the Cap protein of GoAstV-2,rF Ad V4-Cap/GoAstV-2.After 15 passages in LMH cells,the recombinant rFAdV4-Cap/GoAstV-2 was identified by PCR using primers flanking the insertion site of the Cap gene expression cassette and using viral genome DNA extracted from rFAdV4-Cap/GoAstV-2 infected LMH cells as template.LMH cells were in-fected with 15th passage rFAdV4-Cap/GoAstV-2 and indirect immunofluorescence was performed with a polyclonal antibody against Cap protein as the primary antibody.Western blot was carried out with lysates of rFAdV4-Cap/GoAstV-2 infected LMH cells.The in vitro replication dynamic of the 15th passage of the rFAdV4-Cap/GoAstV-2 was also investigated in LMH cells.The results demonstrated that the Cap gene of GoAstV-2 was presented in the genome of the recombinant vi-rus rF AdV4-Cap/Go Ast V-2,and could be expressed stably.The prepared recombinant virus in this study will lay a foundation for developing inactivated bivalent vaccine candidate against co-in-fection of FAdV-4 and GoAstV-2 in goose.

The technologies for ovarian tissue cryopreservation and entire process for ovarian tissue cryopreservation and transplantation were introduced,and the medical equipment configuration was summarized for each stage of ovarian tissue cryopreservation and transplantation.Detailed plans and management methods were proposed for the medical equipment configuration of ovarian tissue cryopreservation and transplantation,and relevant precautions,possible problems and solutions during the process were put forward.References were provided for medical institutions planning to carry out ovarian tissue cryopreservation and transplantation.[Chinese Medical Equipment Journal,2025,46(4):63-69]

Aim To investigate the intervention effect of Rehmannia radix water extract on bleomycin(BLM)-induced pulmonary fibrosis in mice combined with metabolomics and to reveal the potential mechanism,in order to provide new ideas for clinical treatment of pul-monary fibrosis.Methods Male C57BL/6N mice were randomly divided into the control group,model group,pirfenidone group(positive control,PFD,270 mg·kg-1),and low dose(DH-L,4.55 g·kg-1)group,medium dose(DH-M,9.1 g·kg-1)group and high dose(DH-H,18.2 g·kg-1)group of Rehman-nia.Except for the control group,BLM(5 mg·kg-1)was instilled into the trachea to establish the model of pulmonary fibrosis in the other groups.The survival rate,lung index and blood oxygen saturation of mice in each group were evaluated.HE and Masson staining were used to observe the pathological changes of lung tissue.WBP was used to detect lung function.Flow cytometry was used to detect the apoptosis of primary lung cells,ROS and immune cells.ELISA was used to detect the levels of fibrosis markers and inflammatory factors(α-SMA,collagen Ⅰ,collagen Ⅲ,TGF-β1,TNF-α,IL-1 β,and IL-6).Biochemical method was employed to detect the contents of GSH-Px,T-SOD and MDA.Liquid chromatograph mass spectrometer(LC-MS)metabolomics was used to analyze the changes of serum metabolic profile.Results Water extract of Re-hmannia significantly increased the survival rate,oxy-gen saturation and lung function of mice with pulmona-ry fibrosis,reduced the lung coefficient,ameliorated pathological damage and collagen deposition in lung tissue,reduced the levels of apoptosis and oxidative stress,and down-regulated the levels of inflammatory factors in lung tissue.It regulated the levels of metabo-lites such as bile acid metabolism,sphingolipid metabo-lism,and unsaturated fatty acid metabolism.Conclu-sions Water extract of Rehmannia inhibits lung injury and collagen deposition in mice with pulmonary fibrosis by inhibiting inflammatory response,which may be a-chieved by regulating the levels of inflammatory factors through the metabolic pathways of bile acid and sphin-golipid.

Pulmonary alveolar proteinosis(PAP)is a rare progressive respiratory dysfunction disease of the lung characterized by insidious onset and non-specific clinical manifestations,often leading to misdiagnosed and mistreated.Herein,we reported a case of PAP patient admitted to Jiading District Central Hospital with an atypical appearance of alveolar lavage fluid and whose condition improved significantly after treatment with subcutaneous injection of recombinant human granulocyte-macrophage colony stimulating factor(GM-CSF).Additionally,we have reviewed and summarized the relevant literature to enhance the understanding of the diagnosis and treatment of this disease.

Objective To investigate the relationship between prolactin and mild cognitive impairment(MCI)in postmenopausal women with type 2 diabetes mellitus(T2DM).Methods A total of 319 postmenopausal women with T2DM who were hospitalized in the Department of Endocrinology,Drum Tower Hospital,Affiliated Hospital of Medical School,Nanjing University were enrolled in this study from August 2016 to October 2023.All the patients were divided into two groups according whether they had MCI:T2DM group(n=161)and MCI group(n=158).Differences in clinical characteristics were compared between the two groups.Pearson correlation was used to analyze the correlation between sex hormones and cognitive domains,and Logistic regression analysis was used to evaluate the influencing factors for MCI development.Results Serum prolactin levels were significantly lower in the MCI group than in the T2DM group[(5.5±2.1)vs(7.2±2.9)μg/L,P<0.05].Serum prolactin level was positively correlated with mini-mental state examination score,Montreal cognitive assessment score,immediate memory score,visuopatial constructional score,attention score and hippocampal volume(P<0.05),and negatively correlated with processing speed test(time)and executive function test(time)(P<0.05).Logistic regression analysis demonstrated that serum prolactin level was an influencing factor for the risk of MCI in postmenopausal women with T2DM(OR 0.715,95%CI 0.605～0.845,P<0.01).Conclusions The decrease of serum prolactin level is associated with an increased risk of MCI in postmenopausal women with T2DM.

Objective To elucidate the mechanisms of trauma-induced coagulopathy(TIC),clarify the specific pathogenic factors and pathophysiological processes,and discover the effective diagnostic indicators and therapeutic targets.Methods Transcriptomic data of traumatic hemorrhagic shock patients were obtained from the Gene Expression Omnibus(GEO)to identify differentially expressed genes(DEGs).Coagulation-related genes(CRGs)from the Kyoto Encyclopedia of Genes and Genomes(KEGG)were intersected with DEGs.Machine learning algorithms,including least absolute shrinkage and selection operator(LASSO)and random forest(RF),were applied to identify key genes.The CIBERSORT algorithm was used to analyze the correlation between key genes and immune cell infiltration.Through consensus clustering,subtype analysis was conducted on trauma patients to compare the infiltration of immune cells.A rat model of traumatic hemorrhagic shock was established to validate coagulation function and the expression of key genes.Results The dataset included samples from 17 healthy controls and 478 patients with traumatic hemorrhagic shock.A total of 6 315 DEGs were identified under the screening criterion of corrected P<0.05.Gene set enrichment analysis(GSEA)showed that the up-regulated DEGs were significantly enriched in the glucose metabolism pathway,while the down-regulated DEGs were enriched in the immune reaction-related pathways.Through cross-analysis of DEGs and CRGs,a total of 65 differentially expressed coagulation-related genes(DE-CRGs)were screened out.GO functional enrichment showed that these genes were mainly located in secreting granular membranes and platelet α-granules,and were involved in physiological processes such as blood coagulation,regulation of body fluid levels,and wound healing.KEGG pathway analysis revealed that these genes were significantly enriched in pathways such as platelet activation,complement and coagulation cascade reactions,Rap1 signaling pathway,and human cytomegalovirus infection.Six key DE-CRGs were identified through machine learning.Receiver operating characteristic(ROC)curve analysis indicated that these genes had good diagnostic efficacy.CIBERSORT analysis revealed a significant correlation between key genes and immune cell infiltration.Patients were classified into two subtypes based on the six key genes:subtype A was rich in CD8+T cells and activated NK cells,presented an immune-active state;subtype B was mainly composed of monocytes and resting NK cells,with insufficient activation of immune pathways.Animal experiments on rats showed that hemorrhagic shock can lead to coagulation dysfunction.The results of qRT-PCR further confirmed that the expression trend of key genes was consistent with the results of bioinformatics analysis.Conclusion In this study,through transcriptomics and machine learning methods,six key genes closely related to TIC were systematically screened out,namely GNA13,PIK3R3,ITGAM,MAPK14,PPP1CC and LYN,and their close connections with coagulation function and immune infiltration were revealed.Animal experiments have further verified the value of these genes as potential diagnostic and therapeutic targets.

Background and Aims:N6-methyladenosine(m6A)epigenetic modification plays a crucial role in post-transcriptional gene expression regulation and various physiological and pathological processes,including tumorigenesis.The m6A reader IGF2BP2 significantly enhances mRNA stability and translation efficiency and is abnormally expressed in multiple cancers.However,the specific biological function of IGF2BP2 in pancreatic cancer remains unclear.Therefore,this study investigated the expression of the m6A reader IGF2BP2 in pancreatic cancer and its effects on pancreatic cancer cell functions.Methods:The expression levels of m6A-related writers,erasers,and readers were analyzed using The Cancer Genome Atlas(TCGA),the Genotype-Tissue Expression(GTEX)database,and the Gene Expression Omnibus(GEO).Kaplan-Meier survival analysis was conducted to assess the relationship between IGF2BP2 expression and the prognosis of pancreatic cancer patients.Immunohistochemistry was used to validate IGF2BP2 expression in clinical specimens of pancreatic cancer tissues and adjacent normal tissues.Functional experiments,including CCK-8 assay,flow cytometry for cell cycle analysis,colony formation assay,and Transwell migration assay,were performed to evaluate changes in cell proliferation,cell cycle distribution,colony formation ability,and migration capacity after IGF2BP2 knockdown in pancreatic cancer cells.Results:TCGA-GTEX and GEO database analyses showed that IGF2BP2 was highly expressed in pancreatic cancer tissues(both P<0.05)and that its high expression was associated with poor overall survival(both P<0.05).Immunohistochemical staining of clinical specimens confirmed that IGF2BP2 protein expression was higher in pancreatic cancer than in adjacent normal tissue.Functional experiments demonstrated that IGF2BP2 knockdown significantly reduced the proliferation ability of pancreatic cancer cells,arrested more cells in the G0-G1 phase,decreased colony formation,and impaired cell migration(all P<0.05).Conclusion:The m6A reader IGF2BP2 is highly expressed in pancreatic cancer tissues and is closely associated with poor prognosis in patients with this disease.Its mechanism of action may be related to the promotion of cancer cell growth and migration.