T7 RNA polymerase (T7 RNAP) is one of the simplest known RNA polymerases. Its unique structural features make it a critical model for studying the mechanisms of RNA synthesis. This review systematically examines the static crystal structure of T7 RNAP, beginning with an in-depth examination of its characteristic “thumb”, “palm”, and “finger” domains, which form the classic “right-hand-like” architecture. By detailing these structural elements, this review establishes a foundation for understanding the overall organization of T7 RNAP. This review systematically maps the functional roles of secondary structural elements and their subdomains in transcriptional catalysis, progressively elucidating the fundamental relationships between structure and function. Further, the intrinsic flexibility of T7 RNAP and its applications in research are also discussed. Additionally, the review presents the structural diagrams of the enzyme at different stages of the transcription process, and through these diagrams, it provides a detailed description of the complete transcription process of T7 RNAP. By integrating structural dynamics and kinetics analyses, the review constructs a comprehensive framework that bridges static structure to dynamic processes. Despite its advantages, T7 RNAP has a notable limitation: it generates double-stranded RNA (dsRNA) as a byproduct. The presence of dsRNA not only compromises the purity of mRNA products but also elicits nonspecific immune responses, which pose significant challenges for biotechnological and therapeutic applications. The review provides a detailed exploration of the mechanisms underlying dsRNA formation during T7 RNAP catalysis, reviews current strategies to mitigate this issue, and highlights recent progress in the field. A key focus is the semi-rational design of T7 RNAP mutants engineered to minimize dsRNA generation and enhance catalytic performance. Beyond its role in transcription, T7 RNAP exhibits rapid development and extensive application in fields, including gene editing, biosensing, and mRNA vaccines. This review systematically examines the structure-function relationships of T7 RNAP, elucidates the mechanisms of dsRNA formation, and discusses engineering strategies to optimize its performance. It further explores the engineering optimization and functional expansion of T7 RNAP. Furthermore, this review also addresses the pressing issues that currently need resolution, discusses the major challenges in the practical application of T7 RNAP, and provides an outlook on potential future research directions. In summary, this review provides a comprehensive analysis of T7 RNAP, ranging from its structural architecture to cutting-edge applications. We systematically examine: (1) the characteristic right-hand domains (thumb, palm, fingers) that define its minimalistic structure; (2) the structure-function relationships underlying transcriptional catalysis; and (3) the dynamic transitions during the complete transcription cycle. While highlighting T7 RNAP’s versatility in gene editing, biosensing, and mRNA vaccine production, we critically address its major limitation—dsRNA byproduct formation—and evaluate engineering solutions including semi-rationally designed mutants. By synthesizing current knowledge and identifying key challenges, this work aims to provide novel insights for the development and application of T7 RNAP and to foster further thought and progress in related fields.

This study aims to investigate the molecular mechanism by which naringin alleviates cerebral ischemia/reperfusion(CI/R) injury through DRP1/LRRK2/MCU signaling axis. A total of 60 SD rats were randomly divided into the sham group, the model group, the sodium Danshensu group, and low-, medium-, and high-dose(50, 100, and 200 mg·kg~(-1)) naringin groups, with 10 rats in each group. Except for the sham group, a transient middle cerebral artery occlusion/reperfusion(tMCAO/R) model was established in SD rats using the suture method. Longa 5-point scale was used to assess neurological deficits. 2,3,5-Triphenyl tetrazolium chloride(TTC) staining was used to detect the volume percentage of cerebral infarction in rats. Hematoxylin-eosin(HE) staining and Nissl staining were employed to assess neuronal structural alterations and the number of Nissl bodies in cortex, respectively. Western blot was used to determine the protein expression levels of B-cell lymphoma-2 gene(Bcl-2), Bcl-2-associated X protein(Bax), cleaved cysteine-aspartate protease-3(cleaved caspase-3), mitochondrial calcium uniporter(MCU), microtubule-associated protein 1 light chain 3(LC3), and P62. Mitochondrial structure and autophagy in cortical neurons were observed by transmission electron microscopy. Immunofluorescence assay was used to quantify the fluorescence intensities of MCU and mitochondrial calcium ion, as well as the co-localization of dynamin-related protein 1(DRP1) with leucine-rich repeat kinase 2(LRRK2) and translocase of outer mitochondrial membrane 20(TOMM20) with LC3 in cortical mitochondria. The results showed that compared with the model group, naringin significantly decreased the volume percentage of cerebral infarction and neurological deficit score in tMCAO/R rats, alleviated the structural damage and Nissl body loss of cortical neurons in tMCAO/R rats, inhibited autophagosomes in cortical neurons, and increased the average diameter of cortical mitochondria. The Western blot results showed that compared to the sham group, the model group exhibited increased levels of cleaved caspase-3, Bax, MCU, and the LC3Ⅱ/LC3Ⅰ ratio in the cortex and reduced protein levels of Bcl-2 and P62. However, naringin down-regulated the protein expression of cleaved caspase-3, Bax, MCU and the ratio of LC3Ⅱ/LC3Ⅰ ratio and up-regulated the expression of Bcl-2 and P62 proteins in cortical area. In addition, immunofluorescence analysis showed that compared with the model group, naringin and positive drug treatments significantly decreased the fluorescence intensities of MCU and mitochondrial calcium ion. Meanwhile, the co-localization of DRP1 with LRRK2 and TOMM20 with LC3 in cortical mitochondria was also decreased significantly after the intervention. These findings suggest that naringin can alleviate cortical neuronal damage in tMCAO/R rats by inhibiting DRP1/LRRK2/MCU-mediated mitochondrial fragmentation and the resultant excessive mitophagy.
Animals ; Rats, Sprague-Dawley ; Reperfusion Injury/genetics* ; Flavanones/administration & dosage* ; Rats ; Dynamins/genetics* ; Male ; Brain Ischemia/genetics* ; Protein Serine-Threonine Kinases/genetics* ; Signal Transduction/drug effects* ; Humans ; Drugs, Chinese Herbal/administration & dosage*

This study investigates the mechanism by which Xintong Granules improve myocardial ischemia-reperfusion injury(MIRI) through the regulation of gut microbiota and their metabolites, specifically short-chain fatty acids(SCFAs). Rats were randomly divided based on body weight into the sham operation group, model group, low-dose Xintong Granules group(1.43 g·kg~(-1)·d~(-1)), medium-dose Xintong Granules group(2.86 g·kg~(-1)·d~(-1)), high-dose Xintong Granules group(5.72 g·kg~(-1)·d~(-1)), and metoprolol group(10 mg·kg~(-1)·d~(-1)). After 14 days of pre-administration, the MIRI rat model was established by ligating the left anterior descending coronary artery. The myocardial infarction area was assessed using the 2,3,5-triphenyltetrazolium chloride(TTC) staining method. Apoptosis in tissue cells was detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling(TUNEL) assay. Pathological changes in myocardial cells and colonic tissue were observed using hematoxylin-eosin(HE) staining. The levels of tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β), interleukin-6(IL-6), creatine kinase MB isoenzyme(CK-MB), and cardiac troponin T(cTnT) in rat serum were quantitatively measured using enzyme-linked immunosorbent assay(ELISA) kits. The activities of lactate dehydrogenase(LDH), creatine kinase(CK), and superoxide dismutase(SOD) in myocardial tissue, as well as the level of malondialdehyde(MDA), were determined using colorimetric assays. Gut microbiota composition was analyzed by 16S rDNA sequencing, and fecal SCFAs were quantified using gas chromatography-mass spectrometry(GC-MS). The results show that Xintong Granules significantly reduced the myocardial infarction area, suppressed cardiomyocyte apoptosis, and decreased serum levels of pro-inflammatory cytokines(TNF-α, IL-1β, and IL-6), myocardial injury markers(CK-MB, cTnT, LDH, and CK), and oxidative stress marker MDA. Additionally, Xintong Granules significantly improved intestinal inflammation in MIRI rats, regulated gut microbiota composition and diversity, and increased the levels of SCFAs(acetate, propionate, isobutyrate, etc.). In summary, Xintong Granules effectively alleviate MIRI symptoms. This study preliminarily confirms that Xintong Granules exert their inhibitory effects on MIRI by regulating gut microbiota imbalance and increasing SCFA levels.
Animals ; Gastrointestinal Microbiome/drug effects* ; Rats ; Male ; Myocardial Reperfusion Injury/genetics* ; Drugs, Chinese Herbal/administration & dosage* ; Rats, Sprague-Dawley ; Apoptosis/drug effects* ; Humans ; Tumor Necrosis Factor-alpha/metabolism* ; Interleukin-6/genetics* ; Malondialdehyde/metabolism*

OBJECTIVE: CRISPR-Cas protects bacteria from exogenous DNA invasion and is associated with bacterial biofilm formation and pathogenicity. METHODS: We analyzed the type I-F CRISPR-Cas system of Legionella pneumophila WX48, including Cas1, Cas2-Cas3, Csy1, Csy2, Csy3, and Cas6f, along with downstream CRISPR arrays. We explored the effects of the CRISPR-Cas system on the in vitro growth, biofilm-forming ability, and pathogenicity of L. pneumophila through constructing gene deletion mutants. RESULTS: The type I-F CRISPR-Cas system did not affect the in vitro growth of wild-type or mutant strains. The biofilm formation and intracellular proliferation of the mutant strains were weaker than those of the wild type owing to the regulation of type IV pili and Dot/Icm type IV secretion systems. In particular, Cas6f deletion strongly inhibited these processes. CONCLUSION The type I-F CRISPR-Cas system may reduce biofilm formation and intracellular proliferation in L. pneumophila.
Legionella pneumophila/pathogenicity* ; CRISPR-Cas Systems ; Biofilms/growth & development* ; Phenotype ; Bacterial Proteins/metabolism* ; Gene Deletion

Objective:To summarize the clinical and genetic characteristics of late-onset facioscapulohumeral muscular dystrophy type 1 (FSHD1) patients, and to compare the differences between late-onset and classic-onset FSHD1 patients.Methods:A retrospective analysis was conducted on the clinical and genetic data of genetically confirmed late-onset FSHD1 patients (age at onset30 years) between January 2007 and June 2024 from the Department of Neurology of Peking University First Hospital and the First Affiliated Hospital of Fujian Medical University. Classic-onset FSHD1 patients (10 yearsage at onset≤30 years) were matched 1∶1 according to sex and disease duration for comparison. The demographic information, the number of D4Z4 repeat units, the distal D4Z4 methylation levels, FSHD Clinical Score (CS), Clinical Severity Score (CSS), and Age-Corrected Clinical Severity Score (ACSS) of these patients were collected. Survival analysis was performed to compare the outcome of lower extremity involvement between late-onset and classic-onset FSHD1 patients. The correlation of the number of D4Z4 repeat units and D4Z4 methylation level with CS and ACSS was analyzed in late-onset FSHD1 patients.Results:A total of 61 patients with late-onset FSHD1 were enrolled, 33 (54.1%) of whom are female, with an age of 54.0 (46.0, 62.0) years and a disease duration of 14.0 (5.5, 22.5) years. Compared to classic-onset FSHD1 patients, late-onset patients exhibited significantly lower CS [7.0 (5.6, 8.4) vs 6.0 (4.4, 7.7), U=1 416.000, P=0.013], CSS [3.0 (2.8, 3.3) vs 3.0 (2.0, 4.0), U=2 352.000, P=0.010], and ACSS [189.2 (137.1, 241.3) vs 96.8 (61.3, 132.2), U=3 225.500, P0.001], and higher proportion of patients with limb girdle involvement but no facial muscle involvement [18.0% (11/61) vs 6.6% (4/61), χ2=3.725, P=0.054]. Kaplan-Meier survival analysis showed that the onset age of lower extremity involvement in late-onset patients (45 years, 95% CI 42-48 years) was significantly higher than that in classic-onset patients (24 years, 95% CI 21-27 years, χ2=61.012, P0.001). The duration from symptom onset to lower extremity involvement in late-onset patients (15 years, 95% CI 10-20 years) was significantly longer than that in classic-onset patients (8 years, 95% CI 3-13 years, χ2=9.105, P=0.003). Late-onset FSHD1 patients carried higher average distal D4Z4 methylation levels compared to those with classic-onset FSHD1 [46.68% (40.79%,52.57%) vs 41.02% (34.03%,48.00%), U=1 378.500, P=0.014]. Among late-onset FSHD1 patients, cytosine-phosphate-guanine 6 (CpG6) methylation levels were significantly negatively correlated with ACSS ( r=-0.278, P=0.025); the number of D4Z4 repeat units were significantly negatively correlated with ACSS ( r=-0.272, P=0.034);CpG6 methylation levels were significantly negatively correlated with CS ( r=-0.441, P=0.003), while no correlation was found between number of D4Z4 repeat units and CS ( r=-0.161, P=0.310). Conclusions:Compared with classic-onset FSHD1 patients, late-onset FSHD1 patients are associated with a higher degree of distal D4Z4 methylation, along with a milder muscle weakness phenotype, slower disease progression and a higher proportion of cases without facial muscle involvement. The age at onset can be used as a marker of the severity and prognosis in FSHD1.

CRM 197(cross-reacting material 197),a naturally occurring mutant of diphtheria toxin,is a safe and effective vaccine vector and extensively used on developing conjugate or combined vaccines.The mutant loses its enzymatic activity,but fully retains its receptor-binding ability and immunogenicity.In current work,the diphtheria toxin mutant CRM 197 and its fusion proteins with the receptor-binding do-main of botulinum neurotoxin serotype E(EHc)were developed using genetic engineering technology.These recombinant proteins were confirmed by Western blotting and SDS-PAGE.BALB/c mice were im-munized with the CRM197-EHc and EHc-CRM197 fusion proteins,and their immunogenicity was evalua-ted.These two fusion protein molecules,CRM197-EHc and EHc-CRM197,as subunit vaccines,elicited a robust humoral immune response targeting both CRM197 and EHc antigens in the immunized mice.Compared to the mixture of CRM197 and EHc,the mice vaccinated with the fusion proteins(CRM197-EHc and EHc-CRM197)induced higher levels of anti-CRM197 antibodies,and the mice vaccinated with EHc-CRM197 also generated strongest anti-EHc antibodies.Consequently,as a carrier molecule in the fusion protein vaccine,EHc enhances the immunogenicity of CRM197 molecules.Likewise,CRM197 boosts the immunogenicity of EHc in the EHc-CRM197 fusion protein.

CRM 197(cross-reacting material 197),a naturally occurring mutant of diphtheria toxin,is a safe and effective vaccine vector and extensively used on developing conjugate or combined vaccines.The mutant loses its enzymatic activity,but fully retains its receptor-binding ability and immunogenicity.In current work,the diphtheria toxin mutant CRM 197 and its fusion proteins with the receptor-binding do-main of botulinum neurotoxin serotype E(EHc)were developed using genetic engineering technology.These recombinant proteins were confirmed by Western blotting and SDS-PAGE.BALB/c mice were im-munized with the CRM197-EHc and EHc-CRM197 fusion proteins,and their immunogenicity was evalua-ted.These two fusion protein molecules,CRM197-EHc and EHc-CRM197,as subunit vaccines,elicited a robust humoral immune response targeting both CRM197 and EHc antigens in the immunized mice.Compared to the mixture of CRM197 and EHc,the mice vaccinated with the fusion proteins(CRM197-EHc and EHc-CRM197)induced higher levels of anti-CRM197 antibodies,and the mice vaccinated with EHc-CRM197 also generated strongest anti-EHc antibodies.Consequently,as a carrier molecule in the fusion protein vaccine,EHc enhances the immunogenicity of CRM197 molecules.Likewise,CRM197 boosts the immunogenicity of EHc in the EHc-CRM197 fusion protein.

Objective:To summarize the clinical and genetic characteristics of late-onset facioscapulohumeral muscular dystrophy type 1 (FSHD1) patients, and to compare the differences between late-onset and classic-onset FSHD1 patients.Methods:A retrospective analysis was conducted on the clinical and genetic data of genetically confirmed late-onset FSHD1 patients (age at onset30 years) between January 2007 and June 2024 from the Department of Neurology of Peking University First Hospital and the First Affiliated Hospital of Fujian Medical University. Classic-onset FSHD1 patients (10 yearsage at onset≤30 years) were matched 1∶1 according to sex and disease duration for comparison. The demographic information, the number of D4Z4 repeat units, the distal D4Z4 methylation levels, FSHD Clinical Score (CS), Clinical Severity Score (CSS), and Age-Corrected Clinical Severity Score (ACSS) of these patients were collected. Survival analysis was performed to compare the outcome of lower extremity involvement between late-onset and classic-onset FSHD1 patients. The correlation of the number of D4Z4 repeat units and D4Z4 methylation level with CS and ACSS was analyzed in late-onset FSHD1 patients.Results:A total of 61 patients with late-onset FSHD1 were enrolled, 33 (54.1%) of whom are female, with an age of 54.0 (46.0, 62.0) years and a disease duration of 14.0 (5.5, 22.5) years. Compared to classic-onset FSHD1 patients, late-onset patients exhibited significantly lower CS [7.0 (5.6, 8.4) vs 6.0 (4.4, 7.7), U=1 416.000, P=0.013], CSS [3.0 (2.8, 3.3) vs 3.0 (2.0, 4.0), U=2 352.000, P=0.010], and ACSS [189.2 (137.1, 241.3) vs 96.8 (61.3, 132.2), U=3 225.500, P0.001], and higher proportion of patients with limb girdle involvement but no facial muscle involvement [18.0% (11/61) vs 6.6% (4/61), χ2=3.725, P=0.054]. Kaplan-Meier survival analysis showed that the onset age of lower extremity involvement in late-onset patients (45 years, 95% CI 42-48 years) was significantly higher than that in classic-onset patients (24 years, 95% CI 21-27 years, χ2=61.012, P0.001). The duration from symptom onset to lower extremity involvement in late-onset patients (15 years, 95% CI 10-20 years) was significantly longer than that in classic-onset patients (8 years, 95% CI 3-13 years, χ2=9.105, P=0.003). Late-onset FSHD1 patients carried higher average distal D4Z4 methylation levels compared to those with classic-onset FSHD1 [46.68% (40.79%,52.57%) vs 41.02% (34.03%,48.00%), U=1 378.500, P=0.014]. Among late-onset FSHD1 patients, cytosine-phosphate-guanine 6 (CpG6) methylation levels were significantly negatively correlated with ACSS ( r=-0.278, P=0.025); the number of D4Z4 repeat units were significantly negatively correlated with ACSS ( r=-0.272, P=0.034);CpG6 methylation levels were significantly negatively correlated with CS ( r=-0.441, P=0.003), while no correlation was found between number of D4Z4 repeat units and CS ( r=-0.161, P=0.310). Conclusions:Compared with classic-onset FSHD1 patients, late-onset FSHD1 patients are associated with a higher degree of distal D4Z4 methylation, along with a milder muscle weakness phenotype, slower disease progression and a higher proportion of cases without facial muscle involvement. The age at onset can be used as a marker of the severity and prognosis in FSHD1.

The Piezo protein is a non-selective mechanosensitive cation channel that exhibits sensitivity to mechanical stimuli such as pressure and shear stress. It converts mechanical signals into bioelectric activity within cells, thus triggering specific biological responses. In the digestive system, Piezo protein plays a crucial role in maintaining normal physiological activities, including digestion, absorption, metabolic regulation, and immune modulation. However, dysregulation in Piezo protein expression may lead to the occurrence of several pathological conditions, including visceral hypersensitivity, impairment of intestinal mucosal barrier function, and immune inflammation.Therefore, conducting a comprehensive review of the physiological functions and pathological roles of Piezo protein in the digestive system is of paramount importance. In this review, we systematically summarize the structural and dynamic characteristics of Piezo protein, its expression patterns, and physiological functions in the digestive system. We particularly focus on elucidating the mechanisms of action of Piezo protein in digestive system tumor diseases, inflammatory diseases, fibrotic diseases, and functional disorders. Through the integration of the latest research findings, we have observed that Piezo protein plays a crucial role in the pathogenesis of various digestive system diseases. There exist intricate interactions between Piezo protein and multiple phenotypes of digestive system tumors such as proliferation, apoptosis, and metastasis. In inflammatory diseases, Piezo protein promotes intestinal immune responses and pancreatic trypsinogen activation, contributing to the development of ulcerative colitis, Crohn’s disease, and pancreatitis. Additionally, Piezo1, through pathways involving co-action with the TRPV4 ion channel, facilitates neutrophil recruitment and suppresses HIF-1α ubiquitination, thereby mediating organ fibrosis in organs like the liver and pancreas. Moreover, Piezo protein regulation by gut microbiota or factors like age and gender can result in increased or decreased visceral sensitivity, and alterations in intestinal mucosal barrier structure and permeability, which are closely associated with functional disorders like irritable bowel sydrome (IBS) and functional consitipaction (FC). A thorough exploration of Piezo protein as a potential therapeutic target in digestive system diseases can provide a scientific basis and theoretical support for future clinical diagnosis and treatment strategies.