1.Influence of Antigen Type on the Establishment of an Induced Sjögren Syndrome Mouse Model
Wenshuang RONG ; Yuanfei NIU ; Meiting LIU ; Mengyuan YANG ; Shuang CUI ; Lina MA ; Yao FU ; Lianmei WANG ; Junling CAO
Laboratory Animal and Comparative Medicine 2026;46(2):178-190
ObjectiveThis study aims to compare the modeling effects of submaxillary gland antigen and salivary gland antigen in the establishment of Sjögren syndrome (SS) mouse models, and to characterize the phenotypic and immunological features of these models in comparison with spontaneous SS-prone non-obese diabetic (NOD)/LtJ mice. MethodsAdult C57BL/6J mice (equal numbers of males and females) were immunized with submaxillary gland antigen or salivary gland antigen, respectively, combined with Freund's adjuvant to induce SS models. Mice immunized with phosphate-buffered saline (PBS) combined with Freund's adjuvant served as the control group. Immunization was induced via multiple subcutaneous injections in the back with antigen combined with Freund's complete adjuvant (FCA) on Days 1 and 7. A booster immunization was administered via multiple subcutaneous injections in the back with antigen combined with Freund's incomplete adjuvant (FIA) on Day 14. Female NOD/LtJ mice were used as the spontaneous SS model group, with ICR mice as the corresponding control strain for comparative analysis. Body weight, water intake, and salivary flow rate of mice were dynamically monitored for 4 weeks. At the end of the experiment, tissue and serum samples were collected, the weights of submaxillary glands, thymus, and spleen were measured, and organ indices (organ-to-body weight ratios) were calculated. Pathological morphological analysis of the submaxillary gland and spleen was performed with hematoxylin and eosin (HE) staining. Serum interleukin-17 (IL-17) level was detected using enzyme-linked immunosorbent assay (ELISA). Real-time quantitative polymerase chain reaction was used to detect the mRNA expression levels of SS type A (SSA) and SS type B (SSB) in submaxillary gland tissues. ResultsFemale mice in the submaxillary gland antigen group exhibited significantly increased water intake (P<0.05) and reduced salivary flow rate (P<0.05) compared with the female control group. No statistically significant differences were observed in the submaxillary gland index, thymus index and spleen index (P>0.05). Focal lymphocytic infiltration was observed in the submaxillary glands, and the splenic marginal zone was enlarged. Serum IL-17 levels were significantly increased (P<0.05). There was no significant difference in submaxillary gland SSA/SSB expression levels (P>0.05). Compared with the female control group, female mice in the salivary gland antigen group showed no statistically significant differences in water intake, salivary flow rate, submaxillary gland index, and spleen index (P>0.05), whereas the thymus index was significantly reduced (P<0.01). Mild inflammatory cell infiltration and glandular atrophy were observed in the submaxillary glands, and the splenic white pulp and marginal zone were slightly enlarged. Serum IL-17 levels and submaxillary gland SSB mRNA expression levels were significantly increased (P<0.01), whereas no significant change was observed in submaxillary gland SSA expression levels (P>0.05). Compared with the male control group, mild submaxillary gland atrophy was observed in male mice in the submaxillary gland antigen group, whereas no obvious changes were found in other modeling-related indicators (P>0.05). Compared with the ICR control group, NOD/LtJ model mice exhibited elevated water intake (P<0.05), significantly reduced salivary flow rate (P<0.01), no significant differences in the submaxillary gland index or spleen index (P>0.05), but a significantly increased thymus index (P<0.05). Marked focal infiltration was observed in the submaxillary glands, the splenic marginal zone was obviously enlarged, and serum IL-17 concentrations as well as submaxillary gland SSA/SSB expression levels were significantly increased (P<0.05). ConclusionSubmaxillary gland antigen and salivary gland antigen can induce SS-related features in female C57BL/6J mice. The SS-related phenotype is more pronounced in the submaxillary gland antigen group than in the salivary gland antigen group, but weaker than that in spontaneously SS-prone female NOD/LtJ mice. Immunization of male C57BL/6J mice with submaxillary or salivary gland antigens fails to induce an obvious SS phenotype.
2.Research progress on the clinical application and mechanism of Chaihu jia longgu muli decoction in the treatment of neurological diseases
Yimeng KONG ; Zhiyong LIU ; Chengsi DUAN ; Lanyun SHI ; Meina ZHAO ; Mengyuan ZHANG ; Chen YANG
China Pharmacy 2026;37(11):1515-1520
Neurological diseases have high morbidity and disability rates, posing a severe threat to human health. Cli nical manifestations include motor, sensory, cognitive and conscious disorders. Chaihu jia longgu muli decoction is derived from Treatise on Febrile Diseases , with the effects of harmonizing Shaoyang, activating Yang and clearing heat, and tranquilizing the mind. This paper systematically reviews the research progress in clinical application and mechanism of Chaihu jia longgu muli decoction in the field of neurological diseases. It has been found that the decoction shows favorable efficacy in various neurological diseases such as insomnia, depression, epilepsy, vertigo, migraine and vascular dementia. The specific mechanisms are related to regulating neurotransmitter levels, repairing neuronal function, alleviating neuroinflammation, improving mitochondrial dysfunction and regulating intestinal flora. In the future, standardized prospective follow-up cohorts should be established, and core outcome indicators should be clearly defined to strengthen the evidence base. Furthermore, multidisciplinary research should be leveraged to expand the therapeutic value of Chaihu jia longgu muli decoction in the management of neurological diseases.
3.Analysis of influencing factors affecting the efficacy of Shenfukang capsule in the treatment of chronic kidney disease and construction of prediction model
Li TANG ; Mengyuan QIN ; Yufang YANG ; Xiaoqin ZOU ; Zhiwei LIANG ; Xiaobin ZHONG
China Pharmacy 2026;37(13):1740-1745
OBJECTIVE To explore the influencing factors of Shenfukang capsule in the treatment of chronic kidney disease (CKD) and construct a nomogram prediction model for evaluating its therapeutic efficacy. METHODS CKD patients who were hospitalized from July 2019 to August 2022 in the First Affiliated Hospital of Guangxi Medical University and treated with Shenfukang capsule were selected as study subjects. Clinical data of the patients were collected from the hospital’s electronic medical record system, and they were divided into an effective group and an ineffective group based on treatment outcomes. Lasso-Logistic multivariate regression analysis was used to screen the influencing factors of the efficacy of Shenfukang capsule. Using the effectiveness of Shenfukang capsule treatment as the prediction outcome and the screened influencing factors as predictor variables, a nomogram prediction model was constructed using R software. All patients were randomly divided into a training cohort and a validation cohort. The discriminative ability, calibration, and clinical net benefit of the model were evaluated using the receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis, respectively. RESULTS Lasso-Logistic regression analysis revealed that concurrent diabetes mellitus, decreased levels of blood urea nitrogen, triglycerides, and serum phosphorus, as well as prolonged prothrombin time and elevated apolipoprotein AⅠ levels, were influencing factors for reduced efficacy of Shenfukang capsule in CKD treatment. The evaluation results of the nomogram prediction model showed that the area under curve values were 0.745 and 0.797 in the training and validation cohorts, respectively, which were close and both exceeded 0.70, indicating stable predictive performance. The calibration curves demonstrated good agreement in both datasets, suggesting satisfactory calibration performance. The clinical decision curves were positioned above the two extreme reference lines, indicating high clinical benefit of the model. CONCLUSIONS Diabetes mellitus, blood urea nitrogen, triglycerides, apolipoprotein AⅠ, serum phosphorus, and prothrombin time were factors associated with the efficacy of Shenfukang capsule in CKD patients. The nomogram prediction model established in this study may provide a basis for rational clinical application of Shenfukang capsule and for improving its therapeutic efficacy in CKD.
4.Analysis of influencing factors affecting the efficacy of Shenfukang capsule in the treatment of chronic kidney disease and construction of prediction model
Li TANG ; Mengyuan QIN ; Yufang YANG ; Xiaoqin ZOU ; Zhiwei LIANG ; Xiaobin ZHONG
China Pharmacy 2026;37(13):1740-1745
OBJECTIVE To explore the influencing factors of Shenfukang capsule in the treatment of chronic kidney disease (CKD) and construct a nomogram prediction model for evaluating its therapeutic efficacy. METHODS CKD patients who were hospitalized from July 2019 to August 2022 in the First Affiliated Hospital of Guangxi Medical University and treated with Shenfukang capsule were selected as study subjects. Clinical data of the patients were collected from the hospital’s electronic medical record system, and they were divided into an effective group and an ineffective group based on treatment outcomes. Lasso-Logistic multivariate regression analysis was used to screen the influencing factors of the efficacy of Shenfukang capsule. Using the effectiveness of Shenfukang capsule treatment as the prediction outcome and the screened influencing factors as predictor variables, a nomogram prediction model was constructed using R software. All patients were randomly divided into a training cohort and a validation cohort. The discriminative ability, calibration, and clinical net benefit of the model were evaluated using the receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis, respectively. RESULTS Lasso-Logistic regression analysis revealed that concurrent diabetes mellitus, decreased levels of blood urea nitrogen, triglycerides, and serum phosphorus, as well as prolonged prothrombin time and elevated apolipoprotein AⅠ levels, were influencing factors for reduced efficacy of Shenfukang capsule in CKD treatment. The evaluation results of the nomogram prediction model showed that the area under curve values were 0.745 and 0.797 in the training and validation cohorts, respectively, which were close and both exceeded 0.70, indicating stable predictive performance. The calibration curves demonstrated good agreement in both datasets, suggesting satisfactory calibration performance. The clinical decision curves were positioned above the two extreme reference lines, indicating high clinical benefit of the model. CONCLUSIONS Diabetes mellitus, blood urea nitrogen, triglycerides, apolipoprotein AⅠ, serum phosphorus, and prothrombin time were factors associated with the efficacy of Shenfukang capsule in CKD patients. The nomogram prediction model established in this study may provide a basis for rational clinical application of Shenfukang capsule and for improving its therapeutic efficacy in CKD.
5.Role and mechanism of biomimetic remineralization therapy for early enamel demineralization
Xiaohui LIN ; Mengyuan YANG ; Chunnian LI
Chinese Journal of Tissue Engineering Research 2025;29(4):856-865
BACKGROUND:With the improvement of diet and living standards,acidic diet and orthodontic treatment have become the main causes of enamel surface demineralization.As the first step of dental caries,enamel demineralization should be actively intervened.Mechanical grinding has great damage and does not conform to the concept of minimally invasive medicine.Biomimetic remineralization is the best way to deal with enamel demineralization at present. OBJECTIVE:To summarize the mechanism,application and research progress of biomimetic remineralization of early enamel demineralization,and provide ideas for further overcoming the hot issues of biomimetic remineralization. METHODS:English keywords"enamel demineralization,biomimetic remineralization,amelogenin,amorphous calcium phosphate"were used to search PubMed.Chinese keywords"enamel demineralization,biomimetic remineralization,amelogenin"were used to search CNKI.Through screening,72 articles were finally obtained for review. RESULTS AND CONCLUSION:(1)At present,there are drug treatments for enamel demineralization,such as fluoride preparations,laser treatment,resin penetration,remineralization treatment and other treatment methods.Biomimetic remineralization is the most ideal repair method for early enamel demineralization.(2)In the narrow sense,enamel remineralization refers to the mineral re-deposition inside the enamel after early enamel demineralization.In the broad sense,enamel remineralization includes the mineralization deposition on the surface and inside of enamel.(3)Clinical biomimetic remineralization reagents are mainly composed of amelogenin,non amelogenin,amelogenin peptide,casein phosphopeptide-amorphous calcium phosphate complex,etc.The advantages of protein and peptide materials are that they conform to the physiological mechanism and can generate high-strength remineralized materials by inducing orientation.The disadvantages are that the manufacturing process is relatively complex and the cost is high.The remineralization effect of amorphous calcium phosphate complex is good,but it needs to be combined with other materials to play a role.Other calcium phosphate materials are easy to carry and beautiful,but they are easy to cause the formation of dental calculus.(4)Future research should focus on the following aspects:increasing experimental data and clinical results,and clarifying the indications of various methods;explore more biomimetic remineralization methods and find suitable alternative materials;find a reasonable way to combine materials,so that their advantages and disadvantages complement each other.The portability of clinical application can be strengthened to increase the frequency of daily use,so that short-term experimental conclusions can be supported by long-term clinical data.
6.Long-term efficacy analysis of narrow-margin hepatectomy intraoperative radiotherapy for hepatocellular carcinoma
Mengyuan LI ; Yanling WU ; Liming WANG ; Fan WU ; Shulian WANG ; Yueping LIU ; Yongwen SONG ; Ning LI ; Yuan TANG ; Hao JING ; Hui FANG ; Ningning LU ; Shunan QI ; Zhuanbo YANG ; Siye CHEN ; Yexiong LI ; Jianxiong WU ; Qinfu FENG ; Yirui ZHAI ; Bo CHEN
Cancer Research and Clinic 2025;37(5):343-350
Objective:To investigate the long-term efficacy, safety and prognostic factors of intraoperative radiotherapy (IORT) for narrow-margin (resection margin < 1 cm) hepatectomy in patients with hepatocellular carcinoma (HCC) during radical surgery.Methods:A retrospective cohort study was conducted. The data of primary HCC patients undergoing radical surgery and narrow-margin hepatectomy IORT in the Cancer Hospital of the Chinese Academy of Medical Sciences from November 2009 to February 2019 were collected. IORT applied 6 MeV or 9 MeV electron beams and a single irradiation was given to the margin. Kaplan-Meier method was used for the overall survival (OS) and disease-free survival (DFS) analysis; log-rank test was used for survival comparison among subgroups. The recurrence patterns and adverse reactions were recorded. Univariate and multivariate Cox proportional hazards models were used to analyze the factors influencing the OS and DFS.Results:A total of 64 patients were enrolled, with the median age [ M ( Q1, Q3)] of 57 years (49, 63) years. All patients included 55 males (85.9%) and 9 females (14.1%). The median dose of IORT was 15 Gy (range: 12-17 Gy). The median follow-up time was 83.3 (64.4, 91.9) months. The 1-year, 3-year, 5-year, 7-year, 10-year OS rates were 90.4%, 80.6%, 75.5%, 71.4% and 47.6%, respectively; the 1-year, 3-year, 5-year, 7-year,10-year DFS rates were 77.8%, 68.1%, 59.6%, 57.6% and 38.4%, respectively. Univariate Cox regression analysis indicated that preoperative serum alpha-fetoprotein (AFP) > 400 ng/ml was an independent risk factor for poor OS (> 400 ng/ml vs. ≤ 400 ng/ml: HR = 6.57, 95% CI: 2.16-19.96, P < 0.001), while not the independent influencing factor of poor DFS ( HR = 1.71, 95% CI: 0.65-4.52, P = 0.277). The age ≤ 60 years or not, gender, viral hepatitis or not, American Joint Committee on Cancer stage, tumor diameter (> 5 cm or not), tumor number, degree of tumor differentiation, microvascular invasion or not, microsatellite nodules or not, anatomical liver resection or not, and the dose of IORT ≤15 Gy or not were not the independent influencing factors of poor OS and DFS (all P > 0.05). Kaplan-Meier method analysis showed that patients with preoperative serum AFP ≤ 400 ng/ml (48 cases) had better OS compared with those with preoperative serum AFP>400 ng/ml (16 cases) (5-year OS rate: 84.8% vs. 44.9%; 7-year OS rate: 79.9% vs.37.4%), and the difference was statistically significant ( P = 0.002). There was no statistically significant difference in the DFS between the 2 groups ( P = 0.134). During the follow-up, 28 patients (43.8%) relapsed, including 17 cases (26.6%) of early recurrence and 11 cases (17.2%) of late recurrence. No marginal recurrence was observed. There were 22 cases (34.4%) of intrahepatic recurrence alone, 2 cases (3.1%) of extrahepatic recurrence and 4 cases (6.3%) of stimutaneous recurrence inside and outside the liver. The 1-, 3-, 5- and 7-year cumulative recurrence rates inside the liver were 19.0%, 27.2%, 37.4% and 39.3% respectively, and the cumulative recurrence rates outside the liver were 6.4%, 8.0%, 9.6% and 9.6% respectively. There were no adverse reactions above grade 3 in the entire group. There were no surgery-related deaths within 30 d after the operation, and no radiation-induced liver disease occurred. Conclusions:Narrow-margin IORT helps HCC patients receiving hepatectomy to achieve favorable long-term survival and adverse reactions are tolerable. It can be used as a safe and effective adjuvant therapy alternative.
7.Age-related changes in glymphatic pathways in Parkinson′s disease patients based on diffusion tensor imaging analysis along the perivascular space and their relationship with cognitive function
Yang ZHAO ; Changyuan XU ; Yufan CHEN ; Mengyuan ZHUO ; Tao GONG ; Yuanyuan XIANG ; Guangbin WANG
Chinese Journal of Radiology 2025;59(1):64-69
Objective:To investigate the effect of age factor on glymphatic function in patients with Parkinson′s disease (PD) and its potential correlation with overall cognitive performance based on diffusion tensor imaging analysis along the perivascular space(DTI-ALPS) index.Methods:The study was cross-sectional. Clinical and imaging data of 77 PD patients (PD group) who attended the Provincial Hospital of Shandong First Medical University from October 2021 to June 2024 were retrospectively analyzed. In the same period, 30 healthy volunteers matched by age and gender were collected as the normal control (NC) group. All subjects underwent MRI scanning and DTI-ALPS index was calculated based on diffusion tensor imaging. Cognitive functions of 46 patients in the PD group were assessed using the mini-mental state examination (MMSE) and montreal cognitive assessment (MoCA) scores. Independent samples t-tests were used to compare the differences in DTI-ALPS index between the PD and NC groups. After adjusting for confounders, the relationship between DTI-ALPS and age was explored using partial correlation analyses, multiple linear regression models. A mediation model was further developed to explore the mediating effect of DTI-ALPS index between age and cognitive function scores. Results:The DTI-ALPS indices of PD and NC groups were 1.66±0.20 and 1.44±0.17, respectively, and the differences were statistically significant ( t=5.27, P<0.001). The age of patients in the PD group was negatively correlated with the DTI-ALPS index ( r=-0.54, P<0.001), and age (β=-0.467, P<0.001) was an independent influencer of DTI-ALPS index. The DTI-ALPS index was positively correlated with MMSE scores ( r=0.53, P<0.001) and positively correlated with MoCA scores ( r=0.56, P<0.001). The mediation model showed that the DTI-ALPS index fully mediated between age and MMSE scores and partially mediated between age and MoCA scores, with an effect share of 33.25%. Conclusion:Age is an independent risk factor for impaired glymphatic pathway in PD patients, and it may induce cognitive decline in PD patients by exacerbating glymphatic pathway impairment.
8.Comparative analysis of clinical and brain MRI features in methylmalonic acidemia
Mengyuan ZHUO ; Yan YUN ; Chen ZHANG ; Jiaxiang XIN ; Yufan CHEN ; Yang ZHAO ; Changyuan XU ; Guangbin WANG
Chinese Journal of Radiology 2025;59(4):418-424
Objective:To explore brain MRI features of methylmalonic acidemia (MMA).Methods:This observational study retrospectively analyzed the clinical and imaging data of 123 patients with MMA diagnosed at Shandong Provincial Hospital Affiliated to Shandong First Medical University and Qilu Hospital of Shandong University from January 2010 to November 2022. The 123 patients were divided into 7 stages according to age of onset, neonatal period (0 to<1 month), infancy (1 month to<1 year), early childhood (1 to<4 years), preschool (4 to<7 years), school age (7 to<13 years), adolescent (13 to 17 years) and adult (>17 years). All patients underwent brain MRI scanning. The imaging performances were evaluated, including the number, location, morphology of the lesions.Results:Of the 123 patients, 40 were in the neonatal period, 29 in infancy, 13 in early childhood, 9 in preschool, 6 in school age, 13 in adolescence, and 13 in adulthood. The first symptoms of patients in the neonatal period were mainly digestive system abnormalities, such as difficulty in breastfeeding (37.5%, 15/40) and vomiting (25.0%, 10/40), with neurological symptoms gradually becoming the main manifestations from infancy. Seventy-three cases (59.3%) showed significant abnormalities on cranial MRI, including 17 cases with 33 foci in the neonatal period, 23 cases with 53 foci in infancy, 11 cases with 16 foci in early childhood, 2 cases with 2 foci in preschool, 3 cases with 7 foci in school age, 7 cases with 9 foci in adolescence, and 10 cases with 16 foci in adulthood. In neonatal period, the main manifestations were myelin dysplasia (18%,6/33), dilatation of the lateral ventricular system (18%,6/33), and pallidal bulb infarct foci (18%,6/33); in infancy, the main manifestations were hypoplasia or thinning of the corpus callosum (30%,16/53); in early childhood, the main manifestations were pallidal bulb infarct foci (38%,6/16); and the two MRI abnormalities in preschool were pallidum and thalamic infarct foci; in school age, the main manifestations were infarct foci in the chiasmatic nucleus (29%,2/7) and in the caudate nucleus (29%,2/7); in adolescence, the main manifestation was dilatation of the lateral ventricular system (33%,3/9); and in adulthood, the main manifestation was dilatation of the lateral ventricular system (19%,3/16).Conclusion:By staging the age of onset, it is found that the imaging manifestations of MMA patients show significant differences with age, suggesting that there is a dynamic nature of MMA damage to brain structures at different developmental stages.
9.Pristimerin induces Noxa-dependent apoptosis by activating the FoxO3a pathway in esophageal squamous cell carcinoma.
Mengyuan FENG ; Anjie ZHANG ; Jingyi WU ; Xinran CHENG ; Qingyu YANG ; Yunlai GONG ; Xiaohui HU ; Wentao JI ; Xianjun YU ; Qun ZHAO
Chinese Journal of Natural Medicines (English Ed.) 2025;23(5):585-592
Pristimerin, which is one of the compounds present in Celastraceae and Hippocrateaceae, has antitumor effects. However, its mechanism of action in esophageal squamous cell carcinoma (ESCC) remains unclear. This study aims to investigate the efficacy and mechanism of pristimerin on ESCC in vitro and in vivo. The inhibitory effect of pristimerin on cell growth was assessed using trypan blue exclusion and colony formation assays. Cell apoptosis was evaluated by flow cytometry. Gene and protein expressions were analyzed through quantitative reverse transcription-polymerase chain reaction (qRT-PCR), Western blotting, and immunohistochemistry. RNA sequencing (RNA-Seq) was employed to identify significantly differentially expressed genes (DEGs). Cell transfection and RNA interference assays were utilized to examine the role of key proteins in pristimerin?s effect. Xenograft models were established to evaluate the antitumor efficiency of pristimerin in vivo. Pristimerin inhibited cell growth and induced apoptosis in ESCC cells. Upregulation of Noxa was crucial for pristimerin-induced apoptosis. Pristimerin activated the Forkhead box O3a (FoxO3a) signaling pathway and triggered FoxO3a recruitment to the Noxa promoter, leading to Noxa transcription. Blocking FoxO3a reversed pristimerin-induced Noxa upregulation and cell apoptosis. Pristimerin treatment suppressed xenograft tumors in nude mice, but these effects were largely negated in Noxa-KO tumors. Furthermore, the chemosensitization effects of pristimerin in vitro and in vivo were mediated by Noxa. This study demonstrates that pristimerin exerts an antitumor effect on ESCC by inducing AKT/FoxO3a-mediated Noxa upregulation. These findings suggest that pristimerin may serve as a potent anticancer agent for ESCC treatment.
Forkhead Box Protein O3/genetics*
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Humans
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Apoptosis/drug effects*
;
Esophageal Squamous Cell Carcinoma/physiopathology*
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Esophageal Neoplasms/physiopathology*
;
Pentacyclic Triterpenes
;
Animals
;
Cell Line, Tumor
;
Proto-Oncogene Proteins c-bcl-2/genetics*
;
Mice
;
Signal Transduction/drug effects*
;
Mice, Nude
;
Cell Proliferation/drug effects*
;
Triterpenes/pharmacology*
;
Xenograft Model Antitumor Assays
;
Mice, Inbred BALB C
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Male
;
Gene Expression Regulation, Neoplastic/drug effects*
10.Effect of heterologous expression of Scenedesmus quadricauda malic enzyme gene SqME on photosynthetic carbon fixation and lipid accumulation in tobacco leaves.
Yizhen LIU ; Mengyuan LI ; Zhanqian LI ; Yushuang GUO ; Jingfang JI ; Wenchao DENG ; Ze YANG ; Yan SUN ; Chunhui ZHANG ; Jin'ai XUE ; Runzhi LI ; Chunli JI
Chinese Journal of Biotechnology 2025;41(7):2829-2842
Microalgae possess high photosynthetic efficiency, robust adaptability, and substantial biomass, serving as excellent biological resources for large-scale cultivation. Malic enzyme (ME), a ubiquitous metabolic enzyme in living organisms, catalyzes the decarboxylation of malate to produce pyruvate, CO2, and NAD(P)H, playing a role in multiple metabolic pathways including energy metabolism, photosynthesis, respiration, and biosynthesis. In this study, we identified the Scenedesmus quadricauda malic enzyme gene (SqME) and its biological functions, aiming to provide excellent target genes for the genetic improvement of higher plants. Based on the RNA-seq data from S. quadricauda under the biofilm cultivation mode with high CO2 and light energy transfer efficiency and small water use, a highly expressed gene (SqME) functionally annotated as ME was cloned. The physicochemical properties of the SqME-encoded protein were systematically analyzed by bioinformatics tools. The subcellular localization of SqME was determined via transient transformation in Nicotiana benthamiana leaves. The biological functions of SqME were identified via genetic transformation in Nicotiana tabacum, and the potential of SqME in the genetic improvement of higher plants was evaluated. The ORF of SqME was 1 770 bp, encoding 590 amino acid residues, and the encoded protein was located in chloroplasts. SqME was a NADP-ME, with the typical structural characteristics of ME. The ME activity in the transgenic N. tabacum plant was 1.8 folds of that in the wild-type control. Heterologous expression of SqME increased the content of chlorophyll a, chlorophyll b, and total chlorophyll by 20.9%, 26.9%, and 25.2%, respectively, compared with the control. The transgenic tobacco leaves showed an increase of 54.0% in the fluorescence parameter NPQ and a decrease of 30.1% in Fo compared with the control. Moreover, the biomass, total lipids, and soluble sugars in the transgenic tobacco leaves enhanced by 20.5%, 25.7%, and 9.5%, respectively. On the contrary, the starch and protein content in the transgenic tobacco leaves decreased by 22.4% and 12.2%, respectively. Collectively, the SqME-encoded protein exhibited a strong enzymatic activity. Heterologous expressing of SqME could significantly enhance photosynthetic protection, photosynthesis, and biomass accumulation in the host. Additionally, SqME can facilitate carbon metabolism remodeling in the host, driving more carbon flux towards lipid synthesis. Therefore, SqME can be applied in the genetic improvement of higher plants for enhancing photosynthetic carbon fixation and lipid accumulation. These findings provide scientific references for mining of functional genes from S. quadricauda and application of these genes in the genetic engineering of higher plants.
Nicotiana/genetics*
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Photosynthesis/physiology*
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Malate Dehydrogenase/biosynthesis*
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Plant Leaves/genetics*
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Scenedesmus/enzymology*
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Carbon Cycle/genetics*
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Lipid Metabolism/genetics*
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Plants, Genetically Modified/metabolism*

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