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.

Objective To investigate the correlation of dietary lipid intake and apolipoprotein with Helicobacter pylori (Hp) infection combined with gastric mucosal lesions. Methods A retrospective analysis was conducted on 320 patients diagnosed with Hp infection during physical examinations from March 2024 to March 2025. The daily dietary lipid intake of all patients was statistically analyzed. The levels of apolipoprotein A1‌ (Apo-A1) and apolipoprotein B‌ (Apo B) were detected. Logistic regression was used to analyze the risk factors influencing Hp infection combined with gastric mucosal lesions. Results Compared with the non-gastric mucosal lesion group, patients in the gastric mucosal lesion group had higher daily dietary lipid intake, lower Apo-A1, higher Apo B, and higher proportion of family history of gastric cancer (P<0.05). Logistic regression analysis revealed that daily dietary lipid intake, low level of Apo-A1, and high level of Apo B were independent risk factors of Hp infection with gastric mucosal lesion (P<0.05). Conclusion Daily dietary lipid intake, Apo-A1, and Apo B are closely related to Hp infection with gastric mucosal lesion. For patients with high daily dietary lipid intake, decreased Apo-A1 level, increased Apo B level, and complicated Hp infection, it is necessary to further screen gastroscopy to determine whether gastric mucosal lesion occurs.

ObjectiveTo investigate the independent risk factors for concurrent myocardial injury before intervention in patients with primary hepatic carcinoma （PHC）， to construct and validate a nomogram prediction model for the early identification of such patients， and to provide a basis for early clinical prevention and management. MethodsA retrospective analysis was performed for the clinical data of 1 822 patients with PHC in two medical institutions from January 2019 to June 2025， among whom the 1 518 patients from The Third People’s Hospital of Kunming were used as the training set to construct the nomogram prediction model， and the 304 patients from The Second People’s Hospital of Baoshan were used as the validation set. According to the result of high-sensitivity cardiac troponin T measurement before intervention， the patients with PHC were divided into myocardial injury group and non-myocardial injury group. The univariate analysis， the LASSO regression analysis， and the multivariate Logistic regression analysis were used to identify the risk factors of concurrent myocardial injury in PHC patients before intervention， and then a nomogram prediction model was constructed based on these findings. The independent data of the 304 patients in the validation set were used for external validation， and the area under the receiver operating characteristic curve （AUC）， the Hosmer-Lemeshow test， the calibration curve， decision curve analysis， and clinical impact curve were used to assess model performance. ResultsIn the training set， there were 346 patients in the myocardial injury group and 1 172 patients in the non-myocardial injury group， and the prevalence rate of concurrent myocardial injury was 22.79%. The mean age was 56.44±9.45 years， and the male patients accounted for 81.49%. The patients with drinking， smoking， chronic hepatitis B， chronic hepatitis C， hypertension， diabetes， Child-Pugh class A liver disease， BCLC stage B liver disease， or abnormal electrocardiographic findings accounted for 49.34%， 57.44%， 61.73%， 32.48%， 22.66%， 17.19%， 50.53%， 33.86%， and 62.12%， respectively. The univariate analysis， the LASSO regression analysis， and the multivariate Logistic regression analysis showed that age （odds ratio ［OR］=1.051， 95% confidence interval ［CI］： 1.036 — 1.067， P<0.001）， history of diabetes （OR=1.862， 95%CI： 1.346 — 2.574， P<0.001）， electrocardiographic findings （OR=1.446， 95%CI： 1.077 — 1.940， P=0.014）， hemoglobin （HGB） （OR=0.993， 95%CI： 0.988 — 0.998， P=0.003）， albumin （Alb） （OR=0.951， 95%CI： 0.930 — 0.972， P<0.001）， and creatinine （Cr） （OR=1.021， 95%CI： 1.016 — 1.026， P<0.001） were independent influencing factors for myocardial injury in PHC patients. A regression equation was established as Logit（Y）=-3.406+0.050×age+0.621×history of diabetes+0.369×electrocardiogram－0.007×HGB－0.051×Alb+0.021×Cr， and a nomogram prediction model was constructed based on these factors. The Bootstrap internal validation of the model yielded an AUC of 0.743 （95%CI： 0.707 — 0.778）， and the model had an AUC of 0.766 （95%CI： 0.738 — 0.794） in the training set and 0.730 （95%CI： 0.688 — 0.793） in the validation set. The Hosmer-Lemeshow goodness-of-fit test yielded a P value of 0.716 for the training set and 0.408 for the validation set， suggesting that the model had a good degree of fitting. Calibration curves， decision curve analysis， and clinical impact curves in both the training set and the validation set showed that the model had a good clinical application value. ConclusionAge， history of diabetes， electrocardiographic findings， HGB， Alb， and Cr are independent influencing factors for myocardial injury in patients with PHC， and the nomogram prediction model constructed based on these factors has good discriminatory ability， accuracy， and clinical practicability.

Objective To investigate the effect of nutritional deficiency on autophagic flux in human hepatoblastoma HepG2 cells and the autophagy-dependent molecular pathway mediated by ATG5 against nutritional stress.Methods Lentiviral siRNA knockdown of ATG5 was performed to knock down the expression in HepG2 cells,and the transfection was verified by Western blotting and qRT-PCR.HBSS was used to treat HepG2 cells for 0,1,2,3,4,5,6 and 7 h for starvation-induced autophagy.Monodansylcadaverine(MDC)fluorescence staining was employed to detect the formation of intracellular autophagic vesicles.Western blotting was performed to measure the expression changes in microtubule-associated protein 1A/1B-light chain 3(LC3),autophagy receptor protein(sequestosome 1,P62),autophagy-related gene 5(ATG5)and nutrient stress pathway(AMPK/mTOR pathway)related proteins.CCK-8 assay was utilized to test cell proliferation.Results Compared with the HepG2 cells under conventional culture medium,starvation induction resulted in more autophagic vacuoles(accumulation of autofluorescent marker,MDC),which peaked at 6 h of starvation(P<0.000 1),up-regulated protein levels of LC3B-Ⅱ and ATG5(P<0.05),decreased protein expression of P62(P<0.05),gradual activation of the AMPK/mTOR pathway with elapse of starvation time,and increase in the intensity of autophagic flux.However,in the HepG2 cells with ATG5 knockdown,starvation treatment led to decreased ATG5 expression,no significant difference in LC3B-II and P62 changes,inhibited autophagic flux,and suppressed cell proliferation(P<0.000 1).Conclusion Human hepatoblastoma HepG2 cells can regulate autophagic flux to against nutritional stress by inducing ATG5 expression.

Objective To explore the networked association among the dimensions of self-efficacy in patients with rheumatoid arthritis(RA)and to identify core efficacy and bridge efficacy,and provide a basis for formulating precise nursing intervention strategies.Methods A total of 652 RA patients admitted in our hospital from September 2024 to January 2025 were enrolled with convenience sampling.The general information questionnaire and Rheumatoid Arthritis Self-Efficacy Scale(RASE)were used for assessment.Exploratory factor analysis was used to extract efficacy symptom clusters.With aid of R project,network analysis was employed to construct an association network among efficacy dimensions to calculate centrality indicators(strength,closeness,betweenness)to identify core efficacy and bridge efficacy.Results Exploratory factor analysis extracted 7 efficacy symptom clusters,with a cumulative variance contribution rate of 64.539%(P<0.001).Network analysis showed that the network density was 0.143,suggesting that there were moderate correlations among the self-efficacy dimensions."Relaxation efficacy 1(r1)"and"pain efficacy 1(a1)"had the strongest correlation(r=0.73).Interpersonal efficacy 2(i2)had the highest intensity centrality(6.88),and relaxation efficacy 3(r3)had the highest tightness(0.0125),and medication efficacy 1(m1)had the highest mediation(116),which were the core efficacy and bridge efficacy in this network group.Conclusion There are complex network-like correlations among the various dimensions of self-efficacy in RA patients.Interpersonal efficacy is the core driving factor,while relaxation and medication efficacies play the bridging role,jointly influencing the overall level of patients'self-management ability.

Guanylate binding protein subunit β-2(GNB2)is an important part of G protein family.In the process of cell signal transduction,GNB2 plays a structural support and regulatory role in G protein complex,ensuring the correct transmission and amplification of signals,interacting with receptors and regulating vari-ous effector enzymes and ion channels,and mediating a variety of physiological functions.Therefore,GNB2 plays a key role in cell signaling,and participates in the regulation of cell proliferation,differentiation and mi-gration and other biological processes.This article reviews the research progress of GNB2,focusing on its structure,function,regulatory mechanism,disease correlation and importance in tumor research.

Objective:To elucidate the mechanism of acute lung injury (ALI) by investigating the relationship of sirtuin 6 (SIRT6) with lactylation of mitochondrial fission 1 protein (FIS1) and mitophagy in mice.Methods:Twenty-four SPF-grade healthy wild-type C57BL/6 mice of either sex, aged 6-10 weeks, weighing 20-25 g, were divided into 4 groups ( n=6 each) using a table of random numbers: sham operation group (group S), ALI group, ALI + agonist group (group AA), and ALI+ agonist+ lactate group (group AAL). The mouse ALI model was established by intratracheal instillation of lipopolysaccharide 5 mg/kg in anesthetized animals. Immediately after developing the model, UBCS039 30 mg/kg was injected via the tail vein in group AA, UBCS039 30 mg/kg was injected via the tail vein and L-lactic acid sodium 1 mg/g was intraperitoneally injected in group AAL, and vehicle 0.5 ml was given instead in group S. Another 6 Prkn-/- mice were selected and assigned to Prkn-/-+ ALI+ agonist group (group PAA), and UBCS039 30 mg/kg was injected via the tail vein immediately after developing the ALI model. The mice were anesthetized and sacrificed at 12 h after lipopolysaccharide instillation, and the lung tissue was obtained for determination of the FIS1 lactylation and ubiquitination levels, the binding levels of FIS1 to SIRT6 and Parkin (using co-immunoprecipitation), expression of PTEN-induced kinase 1 (PINK1), microtubule-associated protein 1 light chain 3Ⅱ (LC3Ⅱ), and mitochondrial Parkin (by Western blot) and for microscopic examination of the pathological changes (after haematoxylin and eosin staining) which were scored. The wet/dry lung weight (W/D) ratio was calculated, and the apoptosis rate of cells in lung tissues was calculated by TUNEL assay. Results:Compared with group S, the FIS1 lactylation level, W/D ratio, apoptosis rate of cells, and lung injury score were significantly increased in group ALI ( P<0.05). Compared with group ALI, the FIS1 lactylation level, W/D ratio, apoptosis rate of cells, and lung injury score were significantly decreased, the binding level of FIS1 to Parkin and FIS1 ubiquitination level were increased, and the expression of PINK1, LC3Ⅱ and mitochondrial Parkin was up-regulated in group AA ( P<0.05). Compared with group AA, the FIS1 lactylation level was significantly increased, and the binding level of FIS1 to Parkin was decreased in group AAL, and the W/D ratio, apoptosis rate of cells, and lung injury score were significantly increased, the FIS1 ubiquitination level was decreased, and the expression of PINK1, LC3Ⅱ and mitochondrial Parkin was down-regulated in group AAL and group PAA ( P<0.05). Conclusions:SIRT6 inhibits FIS1 lactylation, increases the binding of FIS1 to Parkin, and thus promotes mitophagy, which is involved in the process of ALI in mice.

Objective To study the economic burden caused by healthcare-associated infection(HAI)in patients with severe acute pancreatitis(SAP),and provide theoretical basis for formulating HAI prevention and control measures.Methods Patients with SAP discharged from a tertiary first-class hospital in Jiangxi Province from July 1,2023 to June 30,2024 were selected as the study subjects.Information including demographic characteristics,clinical data,and hospitalization expense were collected.Patients were divided into a HAI group and a non-HAI group according to HAI occurrence.A propensity score matching(PSM)method was used to conduct a 1∶2 ma-tching,and differences in the length of hospital stay and hospitalization expense between the two groups of patients after PSM were compared.Results A total of 709 patients were included in the analysis,out of which 65 cases ex-perienced HAI,with a HAI incidence of 9.17％.After PSM,all 65 patients in the HAI group were successfully matched.The length of hospital stay,total hospitalization expense,expenses of medication and hygiene product of patients in the HAI group were all higher than those in the non-HAI group,and differences were all statistically sig-nificant(all P＜0.001).Patients who experienced≥2 episodes of HAI had a higher economic burden than those who experienced only once(P＜0.05).HAI of bloodstream,abdomen,digestive system,and respiratory system significantly increased the economic burden of patients(all P＜0.05).Conclusion HAI in SAP patients can extend the length of hospital stay and increase economic burden of patients.Targeted infection prevention and control mea-sures should be formulated to reduce the incidence of HAI and save medical resources.

Aim To explore the influence of demethy-lase fat mass and obesity-related genes(FTO)on the abnormal contractile function of diabetic coronary smooth muscle.Methods Smooth muscle specific FTO knockout mice(FTOSMKO)were prepared by Cre-loxP recombinant technology.They were divided into four groups:control(WT)group,diabetes model group(DM),FTO knockout group(FTOSMKO),and FTOSMKO diabetic group(FTOSMKO-DM),with 15 mice in each group.Diabetic mice were prepared by intraperitoneal injection of streptozotocin(STZ);the remaining mice were injected with an equal amount of citric acid-sodi-um citrate buffer.The effects of 5-HTon the contractile response of coronary artery smooth muscle in the four groups of mice were observed by the technique of small-vessel ring tensiometry.Western blot and Dot blot were used to detect the changes of FTO protein and N6-methyladenine(m6A)methylation modification levels in mouse vascular tissues.Results Compared with the WT group,the DM group had significantly higher blood glucose(P＜0.01)and lower body weight(P＜0.05);the level of FTO protein in aorta of DM group increased(P＜0.01),and the level of m6A methylation modification decreased(P＜0.01).The 5-HT-induced contractile response significantly de-creased in the DM group compared with the WT group(P＜0.01),whereas the contractile response signifi-cantly increased in the FTOSMKO-DM group compared with the DM group(P＜0.01);the non-L-type calci-um channel-mediated vascular smooth muscle contrac-tile response was enhanced in the FTOSMKO-DM group,among which,the contractions induced by 1,4,5-triphosphate inositol receptor(IP3R)and caffeine-ac-tivated ranine receptor(RyR)mediated by sarcoplas-mic reticulum calcium release both significantly in-creased(P＜0.05).Conclusions Specific knock-down of smooth muscle FTO improves coronary artery responsiveness to the vasoconstrictor 5-HT in diabetic mice,which may be related to abnormalities in the FTO-mediated 5-HT receptor signaling pathway.

Isoflavones which mainly distributed in leguminous plants have plenty of health benefits.Isoflavone synthase(IFS)is a membrane-associated cytochrome P450 enzyme(CYP450)which carries out the unique aryl-ring migration and hydroxylation.So far,few crystal structures of plant P450s have been obtained.We determined the crystal structure of IFS from Medicago truncatula at 1.9 ? by MAD method using a selenomethionine substituted crystal and conducted molecular docking and mutagenesis study.The structure of IFS complexed with imidazole exhibits the helix Ⅰa-loop-helix Ⅰβ motif which cor-responds to helix Ⅰ of other P450s.Compared with structures of common P450s,IFS/imidazole structure contains an extra domain,i.e.,the γ-domain.The structure reveals a homodimer in which the γ-domain of one molecule interacts with the β-domain of another.The plane of heme group makes an angle of ap-proximately 40° with the helix Ⅰa-loop-helix Ⅰβ motif.Molecular docking combined with mutagenesis study suggested that Trp-128 and Asp-300 might play important roles in substrate binding and recogni-tion.Phe-301,Ser-303 and Gly-305 from the helix Ⅰa-loop-helix Ⅰβ motif may play important roles in the aryl-ring migration.These novel structural features reveal insights into the unique reaction mechanism of IFS and provide a basis for engineering IFS in leguminous crops for health purpose.