1.Establishment and Preliminary Analysis of GP73 Interactome Using Proximity-dependent Labeling Technology
Mu-Yi LIU ; Chang ZHANG ; Meng-Xin YANG ; Xin-Long YAN ; Lu-Ming WAN ; Cong-Wen WEI
Progress in Biochemistry and Biophysics 2026;53(3):711-723
ObjectiveProtein-protein interactions (PPIs) are fundamental to the execution of biological functions within living cells. However, traditional biochemical methods, such as co-immunoprecipitation (Co-IP), often fail to capture transient, weak, or membrane-associated interactions due to the stringent detergent requirements for cell lysis. Proximity labeling (PL) has emerged in recent years as a transformative technology for mapping the proteomes of specific subcellular compartments and identifying dynamic interactomes in situ. Golgi protein 73 (GP73, also known as GOLPH2), a resident type II Golgi transmembrane protein, is a well-recognized clinical biomarker for liver diseases, including hepatocellular carcinoma (HCC). Despite its clinical significance, the comprehensive physiological and pathological functions of GP73 remain partially understood. This study aims to establish an APEX2-mediated proximity labeling system specifically targeting GP73 to map its interactome in a living cellular environment, thereby providing new insights into its molecular roles and regulatory mechanisms. MethodsTo achieve spatial specificity, we first constructed a stable cell line expressing a fusion protein consisting of GP73 and the engineered soybean peroxidase APEX2. The localization of the GP73-APEX2 fusion protein was validated to ensure it correctly targeted the Golgi apparatus. The proximity labeling reaction was initiated by incubating the cells with biotin-phenol (BP) for 30 min, followed by a brief (1 min) treatment with1 mmol/L hydrogen peroxide (H2O2). This catalytic reaction converts BP into highly reactive, short-lived biotin-phenoxyl radicals that covalently attach to endogenous proteins within a small labeling radius of the GP73-APEX2 enzyme. Subsequently, the cells were quenched, and biotinylated proteins were enriched using high-affinity streptavidin-coated magnetic beads. The captured “neighbor” proteins were subjected to on-bead digestion and analyzed via liquid chromatography-tandem mass spectrometry (LC-MS/MS) for high-throughput identification. Rigorous bioinformatics analysis, including Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and protein-protein interaction network mapping, was performed to interpret the biological significance of the identified candidates. ResultsOur results demonstrate the successful establishment of a robust and sensitive APEX2-based proximity labeling system for GP73. We identified a total of 95 high-confidence interacting proteins that were significantly enriched in the GP73 proximity proteome compared to control groups. Bioinformatics analysis revealed that these interactors were predominantly associated with biological processes such as vesicular transport, protein localization, and, most notably, molecular functions related to “ribosome binding” and “translation regulation”. This suggested an unexpected role for the Golgi-resident GP73 in the cellular translation machinery. To validate these findings, we performed targeted biochemical assays which confirmed a direct interaction between GP73 and the subunits of the eukaryotic translation initiation factor 3 (eIF3) complex, specifically EIF3G and EIF3I. Furthermore, functional validation using the surface sensing of translation (SUnSET) assay—a non-radioactive method to monitor protein synthesis—revealed that the overexpression of GP73 significantly promoted global protein translation levels in the cell, whereas its depletion or inhibition resulted in reduced translation efficiency. ConclusionThis study successfully utilized APEX2-mediated proximity labeling to provide the first systematic map of GP73 interactome in living cells. Our findings uncover a novel, unconventional function of GP73 as a regulator of cellular protein translation, likely mediated through its interaction with the eIF3 complex. This discovery significantly broadens our understanding of the biological roles of GP73 beyond its traditional function in the Golgi apparatus and suggests that it may act as a bridge between Golgi-related trafficking and the protein synthesis machinery. Furthermore, the technical framework established in this study provides a valuable template for investigating other complex organelle-associated protein networks and resolving transient macromolecular interactions in various physiological and pathological contexts.
2.Expert consensus on clinical application of Suhuang Zhike Capsules in treatment of respiratory diseases.
Yu MING ; Chang-Rui HUANG ; Bang YU ; Wen-Jing CHANG ; Zeng-Tao SUN ; Wei CHEN ; Hong-Chun ZHANG
China Journal of Chinese Materia Medica 2025;50(3):817-823
Suhuang Zhike Capsules are widely used in clinical practice for the treatment of respiratory diseases and have been included in Medicine Catalogue for National Basic Medical Insurance, Work Injury Insurance, and Maternity Insurance and National Essential Medicines List. However, problems remain, such as unclear definitions of treatment courses and unidentified contraindications for certain populations. Therefore, this consensus was developed collaboratively by clinical experts in traditional Chinese medicine(TCM) related to pulmonary diseases, respiratory, and critical care medicine, as well as methodology and pharmacy experts, adhering strictly to the consensus development procedures established by the China Association of Chinese Medicine for clinical application of Chinese patent medicines, with the aim to guide the correct clinical use of Suhuang Zhike Capsules for the treatment of cough variant asthma, post-infectious cough, and other respiratory diseases. This consensus employed questionnaire surveys and expert interviews to identify clinical concerns based on the PICOS principle and conduct evidence evaluation and GRADE grading. Utilizing nominal group techniques and GRADE networking methods, it resulted in 17 recommendations and consensus suggestions. The consensus further clarifies the indications, TCM syndromes, usage, and clinical safety of Suhuang Zhike Capsules in the treatment of cough variant asthma and post-infectious cough, aiming to promote standardized medication use and facilitate the rational clinical application of Suhuang Zhike Capsules.
Humans
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Drugs, Chinese Herbal/administration & dosage*
;
Consensus
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Capsules
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Respiratory Tract Diseases/drug therapy*
;
Medicine, Chinese Traditional
3.Comprehensive Analysis of Oncogenic, Prognostic, and Immunological Roles of FANCD2 in Hepatocellular Carcinoma: A Potential Predictor for Survival and Immunotherapy.
Meng Jiao XU ; Wen DENG ; Ting Ting JIANG ; Shi Yu WANG ; Ru Yu LIU ; Min CHANG ; Shu Ling WU ; Ge SHEN ; Xiao Xue CHEN ; Yuan Jiao GAO ; Hongxiao HAO ; Lei Ping HU ; Lu ZHANG ; Yao LU ; Wei YI ; Yao XIE ; Ming Hui LI
Biomedical and Environmental Sciences 2025;38(3):313-327
OBJECTIVE:
Hepatocellular carcinoma (HCC) is sensitive to ferroptosis, a new form of programmed cell death that occurs in most tumor types. However, the mechanism through which ferroptosis modulates HCC remains unclear. This study aimed to investigate the oncogenic role and prognostic value of FANCD2 and provide novel insights into the prognostic assessment and prediction of immunotherapy.
METHODS:
Using clinicopathological parameters and bioinformatic techniques, we comprehensively examined the expression of FANCD2 macroscopically and microcosmically. We conducted univariate and multivariate Cox regression analyses to identify the prognostic value of FANCD2 in HCC and elucidated the detailed molecular mechanisms underlying the involvement of FANCD2 in oncogenesis by promoting iron-related death.
RESULTS:
FANCD2 was significantly upregulated in digestive system cancers with abundant immune infiltration. As an independent risk factor for HCC, a high FANCD2 expression level was associated with poor clinical outcomes and response to immune checkpoint blockade. Gene set enrichment analysis revealed that FANCD2 was mainly involved in the cell cycle and CYP450 metabolism.
CONCLUSION
To the best of our knowledge, this is the first study to comprehensively elucidate the oncogenic role of FANCD2. FANCD2 has a tumor-promoting aspect in the digestive system and acts as an independent risk factor in HCC; hence, it has recognized value for predicting tumor aggressiveness and prognosis and may be a potential biomarker for poor responsiveness to immunotherapy.
Humans
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Carcinoma, Hepatocellular/diagnosis*
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Liver Neoplasms/diagnosis*
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Immunotherapy
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Fanconi Anemia Complementation Group D2 Protein/metabolism*
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Prognosis
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Male
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Female
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Middle Aged
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Biomarkers, Tumor/metabolism*
4.Efficacy and Safety of Systemic Thrombolysis in the Treatment of Lower Extremity Fracture Complicated With Distal Deep Vein Thrombosis.
Shi-Qiang LIAO ; Shu-Ming SHI ; Qiang ZHANG ; Chuan-Yong LI ; Guang-Feng ZHENG ; Zhi-Chang PAN ; Jian-Jie RONG
Acta Academiae Medicinae Sinicae 2025;47(2):237-243
Objective To evaluate the efficacy and safety of systemic thrombolysis(ST)and standard anticoagulation(SA)in the treatment of lower extremity fracture complicated with distal deep vein thrombosis(DDVT).Methods We retrospectively analyzed the clinical data of 60 patients with lower extremity fracture complicated with DDVT treated from January 2021 to December 2023.When the lower limb venography indicated a calf thrombus burden score ≥3 points,a retrievable inferior vena cava filter(IVCF)was successfully placed in the healthy femoral vein before orthopedic surgery.The patients who received further anticoagulant or thrombolytic therapy after surgery were allocated into a ST group(n=30,urokinase ST and SA)and a SA group(n=30,only SA).The two groups were compared in terms of calf thrombus burden score,thrombus dissolution rate,IVCF placement time,IVCF retrieval rate,intercepted thrombi,hemoglobin level,platelet count,D-dimer level,and complications.Results There was no statistically significant difference in the calf thrombus burden score between the two groups before treatment(P=0.431).However,after treatment,the scores in both groups decreased(both P<0.001),with the ST group showing lower score than the SA group(P=0.002).The thrombus dissolution rate in the ST group was higher than that in the SA group(P<0.001).There was no statistically significant difference in the IVCF placement time between the two groups(P=0.359),and the IVCF retrieval rate was 100% in both groups.The ST group had fewer intercepted thrombi than the SA group(P=0.002).There was no statistically significant difference in hemoglobin level(P=0.238),platelet count(P=0.914),or D-dimer level(P=0.756)between the two groups before treatment.However,after treatment,both groups showed an increase in platelet count(both P<0.001)and a decrease in D-dimer level(both P<0.001).There was no statistically significant difference in the occurrence of complications between the two groups(P=0.704).Conclusions Both SA and ST demonstrate safety and efficacy in the treatment of lower extremity fractures complicated with DDVT,serving as valuable options for clinical application.Compared with SA,ST not only enhances the thrombus dissolution in the calf but also mitigates the risk of thrombosis associated with IVCF.
Humans
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Venous Thrombosis/therapy*
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Retrospective Studies
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Thrombolytic Therapy/methods*
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Male
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Female
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Middle Aged
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Fractures, Bone/complications*
;
Lower Extremity/injuries*
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Anticoagulants/therapeutic use*
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Aged
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Treatment Outcome
;
Adult
5.Classification and advances in clinical research of artificial colloidal plasma substitutes
Zhengyang CHANG ; Ming LI ; Jianpeng GAO ; Jing ZHANG ; Hua LYU ; Licheng ZHANG
Chinese Journal of Blood Transfusion 2025;38(1):136-141
The number of patients with reduced blood volume due to haemorrhage, fractures, severe infections, extensive burns and tumours is increasing, and traditional blood products are no longer able to meet the increasing clinical demand. Therefore, plasma substitutes have become particularly important in fluid resuscitation, especially artificial colloidal solutions, which have a sustained volume expansion time and a good volume expansion effect, and can significantly improve the circulatory status of patients. This article aims to review the classification of artificial colloidal plasma substitutes and their research progress in clinical practice, in order provide a more rigorous, professional and standardized reference for medicine.
6.Construction and application of pediatric diagnosis and treatment island in a tertiary hospital
Kaiyang GENG ; Hesheng CHANG ; Li ZHANG ; Chen WANG ; Liming YANG ; Ming ZHANG ; Ting WANG ; Zhili JI
Chinese Journal of Hospital Administration 2025;41(6):491-494
Establishing a one-stop diagnosis and treatment mode centered on patients and linked by diseases is of great significance for optimizing the medical process and improving the medical experience. In March 2024, a tertiary hospital integrated pediatric outpatient and emergency resources, established a pediatric diagnosis and treatment island through reasonable department settings, strengthened talent team construction, optimized diagnosis and treatment processes, and established supporting guarantee mechanisms. It was officially put into use in June of the same year, providing one-stop diagnosis and treatment services for children and achieving the goal of " not leaving the island for minor illnesses and not leaving the hospital for major illnesses". Before the operation of island (January May 2024), the complaint rate and waiting time for pediatric outpatient and emergency department were 39 cases per 100 000 patients and 15 to 30 minutes, respectively; After operation (June August 2024), the complaint rate and waiting time decreased to 17 cases per 100 000 people and 10 to 20 minutes respectively; The average monthly comprehensive income of outpatient and emergency departments increased by 33%. The pediatric diagnosis and treatment island mode could assist in the sustainable high-quality development of pediatrics in hospital, and provide references for optimizing outpatient and emergency department management in other tertiary public hospitals. In the future, we should further enrich the service content of the island and strengthen information technology construction.
7.Establishment and validation on reference intervals of systemic inflammatory biomarkers in healthy pregnant women from Henan Province of China
Xianchun MENG ; Yuying LIU ; Shijie ZHANG ; Gaohui WEI ; Qian CHANG ; Fucheng HE ; Wanhai WANG ; Liang MING
Chinese Journal of Laboratory Medicine 2025;48(6):730-736
Objective:To establish the reference intervals (RIs) of systemic immune inflammatory index (SII), platelet to lymphocyte ratio (PLR), neutrophil to lymphocyte ratio (NLR), lymphocyte to monocyte ratio (LMR) and monocyte to lymphocyte ratio (MLR) in healthy pregnant women in Henan province, China.Methods:A retrospective analysis was conducted on the data of the healthy pregnant women without a history of adverse pregnancy events who participated in health check-ups from August 2016 to February 2019. A total of 4 016 healthy pregnant women were selected for establishing RIs. Data from healthy adult control group were derived from the healthy adult cohort in Henan established earlier by our team, and the Propensity Score Matching analysis was used and 3 595 healthy adult women and 3 595 healthy pregnant women to compare the indicators between the two groups. The RIs of the above indicators were established using the indirect method with a 95% confidence interval. The Tukey Rule was used to identify and remove outliers. The RIs were stratified and grouped based on the differences in each indicator during the pregnancy: SII: 3 929 cases, including 712 in the first trimester, 1 947 in the second trimester, and 1, 270 in the third trimester; PLR: 3 927 cases, no grouping; NLR: 3 925 cases, including 712 in the first trimester and 3 213 in the second and third trimesters; LMR: 3 925 cases, including 723 in the first trimester, 1 942 in the second trimester, and 1 260 in the third trimester; MLR: 3 904 cases, including 721 in the first trimester, 1 928 in the second trimester, and 1 255 in the third trimester. After the RIs were established, another 396 healthy pregnant women without a history of adverse pregnancy events who participated in health check-ups from February to April 2019 were selected for the validation of the RIs.Results:SII, NLR, LMR, MLR, and PLR differ significantly between healthy adult women and healthy pregnant women. There were significant differences in SII, LMR, and MLR among the three trimesters ( P<0.05). NLR in the first trimester was significantly lower than that in the second and third trimesters ( P<0.05), while there was no significant difference between the second and third trimester ( P=0.124). PLR only showed significant differences between the second and third trimester ( P<0.05), while no significant differences were found among the other groups. Based on the above results, the stratified RIs of each index in healthy pregnant population were established and verified. SII: first trimester (341-1 426)×10 9/L, second trimester (437-1 680)×10 9/L, third trimester (379-1 580)×10 9/L; PLR: 73-215; NLR: first trimester 1.78-5.60, second and third trimester 2.21-6.74; LMR: first trimester 2.20-6.61, second trimester 1.85-5.42, third trimester 1.63-4.82; MLR: first trimester 0.14-0.42, second trimester 0.17-0.49, third trimester 0.18-0.55. The rejection rate of 396 cases was less than 10%. Conclusions:The RIs of SII, NLR, LMR, MLR and PLR for healthy pregnant women in Hernan province of China were established and validated, and4 could be used in clinical practice.
8.Involvement of sympathetic nerve in the regulation of disuse atrophy of skeletal muscles: a preliminary study
Dongliang CHENG ; Mingming ZHANG ; Jiang LIU ; Junmin SHEN ; Zhongqi WANG ; Xinyu SUN ; Duanyang WANG ; Feifan CHANG ; Haobo ZHANG ; Pincong FU ; Ming CHEN ; Yi LI ; Pengbin YIN ; Licheng ZHANG ; Peifu TANG
Chinese Journal of Orthopaedic Trauma 2025;27(3):242-249
Objective:To investigate the changes in sympathetic nerve activity after lower limb immobilization and the role of sympathetic nerve in regulating disuse atrophy of skeletal muscles.Methods:The experiment was divided into the following 3 parts: ① Twelve 8-week-old male C57 mice were randomly divided into a blank control group and a hind limb fixation group ( n=6). The blank control group received no intervention while the hind limb fixation group received splint fixation of the hind limbs for 2 weeks before the musculoskeletal multi-dimensional characterization was completed at the behavioral, pathological and molecular levels. ② Thirty-six 8-week-old male C57 mice were selected and randomly divided into a control group and 5 hind limb fixation groups (for 1, 3, 5, 7 and 14 days) ( n=6). The control group was fed normally until 14 days without any intervention while the 5 hind limb fixation groups were sampled after fixation for 1, 3, 5, 7 and 14 days, respectively. The level of norepinephrine in the serum and the expression level of tyrosine hydroxylase (TH), a marker of sympathetic nerve activity in the paraventricular nucleus of hypothalamus (PVN), were detected to observe the plasticity of sympathetic nerve activity. ③ Eighteen 8-week-old male C57 mice were selected and randomly divided into a blank control group, a hind limb fixation group and a hind limb fixation plus medication group ( n=6). The blank control group received no intervention while the 2 fixation groups were injected with phosphate buffer (PBS) and propranolol hydrochloride solution for 2 consecutive weeks, respectively. The parameters related to the skeletal muscles were compared between the 3 groups. Results:① Compared with the control group, the mass and function of skeletal muscles in the hind limb fixation group were statistically significantly decreased ( P<0.05). ② The levels of serum norepinephrine [(3.27±1.03) ng/mL, (9.21±1.05) ng/mL, (6.36±0.88) ng/mL, (3.84±1.00) ng/mL, and (3.91±0.75) ng/mL] and the PVN TH levels (42.00%±5.38%, 61.67%±5.57%, 55.82%±3.11%, 50.90%±2.53%, and 39.17%±9.07%) in the 5 hind limb fixation groups (for 1, 3, 5, 7 and 14 days) were significantly higher than those in the control group [(1.81±0.72)] ng/mL and 23.33%±5.50%] ( P<0.05). ③ The wet weight of the gastrocnemius muscle [(93.50±4.32) mg] and the cross-section area of the tibial anterior muscle [(1,180.00±95.09) μm 2] in the hind limb fixation plus medication group were increased significantly compared with those in the hind limb fixation group [(80.83±9.99) mg and (907.80±121.00) μm 2] ( P<0.05). Conclusions:Overactivation of the sympathetic nervous system occurs in the mice model of skeletal muscle disuse atrophy after hind limb fixation. Inhibition of sympathetic nerve activity may reduce the severity of skeletal muscle atrophy at the lower limbs.
9.Mechanism of Tougu Xiaotong Capsules regulating Malat1 and mi R-16-5p ceRNA to alleviate "cholesterol-iron" metabolism disorder in osteoarthritis chondrocytes.
Chang-Long FU ; Yan-Ming LIN ; Shu-Jie LAN ; Chao LI ; Zi-Hong ZHANG ; Yue CHEN ; Ying-Rui TONG ; Yan-Feng HUANG
China Journal of Chinese Materia Medica 2025;50(15):4363-4371
From the perspective of competitive endogenous RNA(ceRNA) constructed by metastasy-associated lung adenocarcinoma transcript 1(Malat1) and microRNA 16-5p(miR-16-5p), the improvement mechanism of Tonggu Xiaotong Capsules(TGXTC) on the imbalance and disorder of "cholesterol-iron" metabolism in chondrocytes of osteoarthritis(OA) was explored. In vivo experiments, 60 8-week-old C57BL/6 mice were acclimatized and fed for 1 week and then randomly divided into two groups: blank group(12 mice) and modeling group(48 mice). The animals in modeling group were anesthetized by 5% isoflurane inhalation, which was followed by the construction of OA model. They were then randomly divided into model group, TGXTC group, Malat1 overexpression group, and TGXTC+Malat1 overexpression(TGXTC+Malat1-OE) group, with 12 mice in each group. The structural changes of mouse cartilage tissues were observed by Masson staining after the intervention in each group. RT-PCR was employed to detect the mRNA levels of Malat1 and miR-16-5p in cartilage tissues. Western blot was used to analyze the protein expression of ATP-binding cassette transporter A1(ABCA1), sterol regulatory element-binding protein(SREBP), cytochrome P450 family 7 subfamily B member 1(CYP7B1), CCAAT/enhancer-binding protein homologous protein(CHOP), acyl-CoA synthetase long-chain family member 4(ACSL4), and glutathione peroxidase 4(GPX4) in cartilage tissues. In vitro experiments, mouse chondrocytes were induced by thapsigargin(TG), and the combination of Malat1 and miR-16-5p was detected by double luciferase assay. The fluorescence intensity of Malat1 in chondrocytes was determined by fluorescence in situ hybridization. The miR-16-5p inhibitory chondrocyte model was constructed. RT-PCR was used to analyze the levels of Malat1 and miR-16-5p in chondrocytes under the inhibition of miR-16-5p. Western blot was adopted to analyze the regulation of TG-induced chondrocyte proteins ABCA1, SREBP, CYP7B1, CHOP, ACSL4, and GPX4 by TGXTC under the inhibition of miR-16-5p. The results of in vivo experiments showed that,(1) compared with model group, TGXTC group exhibited a relatively complete cartilage layer structure. Compared with Malat1-OE group, TGXTC+Malat1-OE group showed alleviated cartilage surface damage.(2) Compared with model group, TGXTC group had a significantly decreased Malat1 mRNA level and an increased miR-16-5p mRNA level in mouse cartilage tissues(P<0.01).(3) Compared with the model group, the protein levels of ABCA1 and GPX4 in the cartilage tissue of mice in the TGXTC group increased, while the protein levels of SREBP, CYP7B1, CHOP and ACSL4 decreased(P<0.01). The results of in vitro experiments show that,(1) dual-luciferase was used to evaluate that miR-16-5p has a targeting effect on the Malat1 gene.(2)Compared with TG+miR-16-5p inhibition group, TG+miR-16-5p inhibition+TGXTC group had an increased mRNA level of miR-16-5p and an decreased mRNA level of Malat1(P<0.01).(3) Compared with TG+miR-16-5p inhibition group, TG+miR-16-5p inhibition+TGXTC group exhibited increased expression of ABCA1 and GPX4 proteins and decreased expression of SREBP, CYP7B1, CHOP, and ACSL4 proteins(P<0.01). The reasults showed that TGXTC can regulate the ceRNA of Malat1 and miR-16-5p to alleviate the "cholesterol-iron" metabolism disorder of osteoarthritis chondrocytes.
Animals
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MicroRNAs/metabolism*
;
RNA, Long Noncoding/metabolism*
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Chondrocytes/drug effects*
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Drugs, Chinese Herbal/pharmacology*
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Mice, Inbred C57BL
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Mice
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Osteoarthritis/drug therapy*
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Iron/metabolism*
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Male
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Cholesterol/metabolism*
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Humans
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Capsules
;
RNA, Competitive Endogenous
10.Structural and Spatial Analysis of The Recognition Relationship Between Influenza A Virus Neuraminidase Antigenic Epitopes and Antibodies
Zheng ZHU ; Zheng-Shan CHEN ; Guan-Ying ZHANG ; Ting FANG ; Pu FAN ; Lei BI ; Yue CUI ; Ze-Ya LI ; Chun-Yi SU ; Xiang-Yang CHI ; Chang-Ming YU
Progress in Biochemistry and Biophysics 2025;52(4):957-969
ObjectiveThis study leverages structural data from antigen-antibody complexes of the influenza A virus neuraminidase (NA) protein to investigate the spatial recognition relationship between the antigenic epitopes and antibody paratopes. MethodsStructural data on NA protein antigen-antibody complexes were comprehensively collected from the SAbDab database, and processed to obtain the amino acid sequences and spatial distribution information on antigenic epitopes and corresponding antibody paratopes. Statistical analysis was conducted on the antibody sequences, frequency of use of genes, amino acid preferences, and the lengths of complementarity determining regions (CDR). Epitope hotspots for antibody binding were analyzed, and the spatial structural similarity of antibody paratopes was calculated and subjected to clustering, which allowed for a comprehensively exploration of the spatial recognition relationship between antigenic epitopes and antibodies. The specificity of antibodies targeting different antigenic epitope clusters was further validated through bio-layer interferometry (BLI) experiments. ResultsThe collected data revealed that the antigen-antibody complex structure data of influenza A virus NA protein in SAbDab database were mainly from H3N2, H7N9 and H1N1 subtypes. The hotspot regions of antigen epitopes were primarily located around the catalytic active site. The antibodies used for structural analysis were primarily derived from human and murine sources. Among murine antibodies, the most frequently used V-J gene combination was IGHV1-12*01/IGHJ2*01, while for human antibodies, the most common combination was IGHV1-69*01/IGHJ6*01. There were significant differences in the lengths and usage preferences of heavy chain CDR amino acids between antibodies that bind within the catalytic active site and those that bind to regions outside the catalytic active site. The results revealed that structurally similar antibodies could recognize the same epitopes, indicating a specific spatial recognition between antibody and antigen epitopes. Structural overlap in the binding regions was observed for antibodies with similar paratope structures, and the competitive binding of these antibodies to the epitope was confirmed through BLI experiments. ConclusionThe antigen epitopes of NA protein mainly ditributed around the catalytic active site and its surrounding loops. Spatial complementarity and electrostatic interactions play crucial roles in the recognition and binding of antibodies to antigenic epitopes in the catalytic region. There existed a spatial recognition relationship between antigens and antibodies that was independent of the uniqueness of antibody sequences, which means that antibodies with different sequences could potentially form similar local spatial structures and recognize the same epitopes.

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