1.Evolution and interpretation of diagnostic criteria for infective endocarditis
Hongkun QING ; Weiteng WANG ; Xuhua JIAN
Chinese Journal of Clinical Thoracic and Cardiovascular Surgery 2026;33(01):30-36
Infective endocarditis (IE) is a life-threatening infectious disease. Although histopathological examination remains the gold standard for definitive diagnosis, it is performed in only a minority of patients; thus, the diagnosis of IE continues to rely predominantly on clinical manifestations. However, IE presents with highly variable systemic symptoms that often lack cardiac-specific features, posing significant diagnostic challenges. To address this complexity, multiple diagnostic criteria have been developed, integrating clinical presentation, imaging findings, and microbiological evidence. Over the past three decades, substantial shifts in the microbiological and epidemiological profiles of IE, coupled with advances in imaging modalities and laboratory diagnostics, have profoundly influenced diagnostic approaches, driving continuous refinement of diagnostic criteria. This review provides a comprehensive overview of the major diagnostic criteria for IE, traces their historical evolution, evaluates recent updates and diagnostic performance, and offers theoretical insights and practical implications to guide future research.
2.Clinical efficacy of cardiovascular surgery combined with preoperative immunosuppression for Behçet's disease: A retrospective cohort study in a single center
Fanyu CHEN ; Lanxin YE ; Ziyan XU ; Oudi CHEN ; Lixi GAN ; Hongkun QING ; Weiteng WANG ; Xin LI ; Yang CUI ; Xuhua JIAN
Chinese Journal of Clinical Thoracic and Cardiovascular Surgery 2026;33(09):1448-1456
Objective To evaluate the effectiveness of preoperative immunosuppressive therapy combined with surgical intervention for Behçet's disease. Methods A retrospective study was conducted on Behçet's disease patients who underwent cardiovascular surgery at Guangdong Provincial People's Hospital from 2012 to 2021. Patients were divided into an immunosuppressive group and a non-immunosuppressive group based on whether they received immunosuppressive therapy before surgery. The complications and long-term survival rates of the two groups were analyzed. Results A total of 28 patients were included, among which 2 patients underwent reoperation, a total of 30 surgeries were performed, including 16 males (53.3%), and the age at diagnosis was 37 (31, 45) years. There were 15 surgeries in the immunosuppressive group and 15 surgeries in the non-immunosuppressive group. Compared with the non-immunosuppressive group, the incidence of complications during hospitalization in the immunosuppressive group was lower (13.3% vs. 53.3%, P=0.008). One patient died in hospital, and the rest were discharged and followed up, with a median follow-up time of 38.7 (15.1, 57.3) months, and there was no statistically significant difference in long-term survival rate between the two groups (73.3% vs. 93.3%, P=0.158). There was no statistical difference in the cumulative incidence of complications one month (20% vs. 53%, P=0.058) and one year (27% vs. 60%, P=0.065) after surgery between the immunosuppressive group and the non-immunosuppressive group, but there was a statistical difference in the cumulative incidence of complications three years after surgery (47% vs. 92%, P=0.002). Conclusion Surgical treatment can save lives in Behçet's disease patients with cardiovascular diseases, but the incidence of postoperative complications is high. Timely use of immunosuppressants before cardiovascular surgery can reduce the incidence of postoperative complications.
3.Effects of chronic stress on hypothalamic appetite-regulating factors in mice
Lifeng YIN ; Qing LIU ; Jian ZHU ; Chenxu WANG ; Tianyu ZHENG ; Yongheng ZHU ; Fengfeng MO
Academic Journal of Naval Medical University 2025;46(1):72-78
Objective To explore the effects of chronic stress and stress cessation on hypothalamic appetite regulators in mice,and to explore the stress-dependent mechanism of appetite change.Methods A total of 32 male C57BL/6 mice were randomly divided into control(Ctrl)group(n=16)and chronic unpredictable mild stress(CUMS)group(n=16).The mice in the CUMS group were given CUMS to establish the stress model,and those in the Ctrl group were fed normally.The food intake and weight of mice were recorded.The CUMS model was verified through tail suspension experiments and forced swimming experiments.Eight mice in the Ctrl group and 8 mice in the CUMS group were randomly sacrificed at the 12th week.The Ctrl group was re-grouped into the cessation-control(C-Ctrl)group(n=8),the CUMS group was re-grouped into the cessation-stress(C-CUMS)group(n=8),and the mice were sacrificed at the 15th week.The mRNA and protein levels of appetite-regulating factors,including orexin 1 receptor(OX1R),leptin receptor(LEPR)and agouti-related protein(AgRP)in the hypothalamus,were detected by quantitative polymerase chain reaction and immunochemistry.Results From week 2 to week 11 of stress,the food intake of the mice in the CUMS group was significantly higher than that in the Ctrl group(all P<0.05),while there was no significant difference in body weight between the 2 groups within 11 weeks(all P>0.05).Compared with the Ctrl group,the immobility durations of forced swimming and tail suspension of the CUMS group were markedly longer after 11 weeks(both P<0.01),indicating successful modeling.AgRP and OX1R mRNA expression in the hypothalamus of the CUMS group was significantly increased(both P<0.01),while LEPR mRNA expression was significantly decreased(P<0.01);AgRP protein in the hypothalamic arcuate nucleus of the CUMS group was significantly higher than that of the Ctrl group(P<0.05),and LEPR protein was markedly lower than that of the Ctrl group(P<0.01).However,after 3 weeks of stress cessation,the C-CUMS group had less food intake and lower body weight than the C-Ctrl group(both P<0.05).The LEPR mRNA of the C-CUMS group was significantly increased(P<0.01),while AgRP and OX1R mRNA were not significantly different(both P>0.05).There was no significant difference in AgRP protein levels between the C-CUMS group and the C-Ctrl group(P>0.05),while LEPR protein level of the C-CUMS group was significantly higher than that of the C-Ctrl group(P<0.01).Conclusion CUMS can lead to increased appetite in mice,which may involve the functional regulation of LEPR and AgRP.After the stress cessation,the appetite decreases,which may involve the functional regulation of LEPR.
4.PD-1-mediated CD4+T cell exhaustion exacerbates gut microbiota translocation in mouse model of sepsis
Bin QING ; Xinxin KONG ; Dongfan YE ; Chuangye WANG ; Jian ZHANG ; Bin WANG ; Xiaoou HUANG ; Nanbo WANG ; Hang QIAN ; Zhi XU
Journal of Army Medical University 2025;47(19):2302-2314
Objective To investigate the characteristics of immune exhaustion in sepsis and analyze its association with gut microbiota translocation.Methods A total of 130 mice were randomly divided into a cecal ligation and puncture(CLP)group(n=100)and a Sham group(n=30)Mouse model of sepsis was established with CLP procedure.Flow cytometry was used to analyze the proportions of peripheral blood CD4+T and CD8+T cells and programmed cell death protein 1(PD-1)positive T cell subsets in mice.Bacterial colonization in organs such as the heart,liver and kidneys was quantified by plating homogenates of the organs.Pathological changes in immune organs were observed with HE staining.The expression and localization of CD4?,CD8?,and PD-1?cells in immune organs were detected with immunohistochemical staining,and Image J software was employed for subsequent quantification of the number of the positive cells.Results HE staining demonstrated that immune organs exhibited varying degrees of pathological damages with disease progression.Compared with the Sham mice,the CLP mice exhibited significantly increased bacterial colonization in parenchymal organs and peripheral blood(P<0.05),notably in the liver,which showed the most severe infection.In the CLP group,the proportion of CD4+T lymphocytes in peripheral blood at days 1,3,and 5 postoperatively was decreased by 56%,70.57%,and 87.42%,respectively,when compared with the Sham group(P<0.001).The proportion of CD8+T lymphocytes was decreased by 48.33%relative to the Sham group only at day 5(P<0.001).In contrast,the proportion of CD4+T cell subsets expressing PD-1 was increased to 673.08,423.08,and 600 times that of the Sham group,respectively,at the same postoperative time points(P<0.001).Immunohistochemical results showed that,in the CLP group,the proportion of CD4+T cells in the thymus,spleen,and mesenteric lymph nodes was increased to 7.65,2.66,and 3.7 times that of the Sham group,respectively,at the early-stage peak(P<0.001),and then these proportions were decreased by 82.8%(P<0.001),41.9%(P<0.01),and 60.15%(P<0.001),respectively,at the late-stage trough when compared with the early-stage peak in the corresponding organs.The proportion of CD8+positive cells was increased in the early stage and then decreased insignificantly,while the proportion of PD-1+positive cells was increased continuously,and reached 6.24,13.9,and 20.96 times that of the Sham group at the peak in the thymus,spleen,and mesenteric lymph nodes respectively(P<0.001),with their expression regions showing a rough overlap with those of CD4+cells.Conclusion During sepsis,the inflammatory response can cause severe damage to immune organs and persistent exhaustion of CD4?T lymphocytes,leading to declined defenses against infection,which may be the main causes for exacerbated gut microbiota translocation and then systemic infection.
5.Veronica anagallis-aquatica L. iridoid glycosides alleviate heart failure via metabolites homoveratrumic acid and 2-hydroxy-3,4-dimethoxybenzoic acid mediated by the gut microbiota.
Manjiong WANG ; Xiaobo GUO ; Hanfang LIU ; Xiao LI ; Yue YAO ; Qing FU ; Yu JIN ; Shuaishuai NI ; Xiaokang LI ; Chaojiang XIAO ; Bei JIANG ; Conglong XIA ; Jian LI ; Yixiang XU
Acta Pharmaceutica Sinica B 2025;15(6):3338-3342
The iridoid glycosides from Veronica anagallis-aquatica L. alleviate heart failure by modulating the gut microbiota and influencing the production of two metabolites with potential antihypertrophic effects, HVA and 2OH-VA.Image 1.
6.Expert Consensus on Clinical Application of Qinbaohong Zhike Oral Liquid in Treatment of Acute Bronchitis and Acute Attack of Chronic Bronchitis
Jian LIU ; Hongchun ZHANG ; Chengxiang WANG ; Hongsheng CUI ; Xia CUI ; Shunan ZHANG ; Daowen YANG ; Cuiling FENG ; Yubo GUO ; Zengtao SUN ; Huiyong ZHANG ; Guangxi LI ; Qing MIAO ; Sumei WANG ; Liqing SHI ; Hongjun YANG ; Ting LIU ; Fangbo ZHANG ; Sheng CHEN ; Wei CHEN ; Hai WANG ; Lin LIN ; Nini QU ; Lei WU ; Dengshan WU ; Yafeng LIU ; Wenyan ZHANG ; Yueying ZHANG ; Yongfen FAN
Chinese Journal of Experimental Traditional Medical Formulae 2025;31(4):182-188
The Expert Consensus on Clinical Application of Qinbaohong Zhike Oral Liquid in Treatment of Acute Bronchitis and Acute Attack of Chronic Bronchitis (GS/CACM 337-2023) was released by the China Association of Chinese Medicine on December 13th, 2023. This expert consensus was developed by experts in methodology, pharmacy, and Chinese medicine in strict accordance with the development requirements of the China Association of Chinese Medicine (CACM) and based on the latest medical evidence and the clinical medication experience of well-known experts in the fields of respiratory medicine (pulmonary diseases) and pediatrics. This expert consensus defines the application of Qinbaohong Zhike oral liquid in the treatment of cough and excessive sputum caused by phlegm-heat obstructing lung, acute bronchitis, and acute attack of chronic bronchitis from the aspects of applicable populations, efficacy evaluation, usage, dosage, drug combination, and safety. It is expected to guide the rational drug use in medical and health institutions, give full play to the unique value of Qinbaohong Zhike oral liquid, and vigorously promote the inheritance and innovation of Chinese patent medicines.
7.Comparison of posterior C2-3 fixation combined with bucking bar technique and posterior C2-3 fixation alone in treatment of unstable Hangman fractures
Hao ZHANG ; Qing WANG ; Jian ZHANG ; Guangzhou LI ; Gaoju WANG
Chinese Journal of Tissue Engineering Research 2025;29(9):1848-1854
BACKGROUND:Types II,IIA,and III of Hangman fractures often require surgical treatment,and the selection of surgical methods is controversial.Current surgeries have shortcomings such as incomplete reduction and malunion after surgery.In the early stage,our team used C2-3 lag screws combined with a bucking bar.Intermittent pushing of the C2 vertebral body in the oropharynx has achieved satisfactory clinical results.However,the preliminary studies included few samples and lacked a control group for comparison. OBJECTIVE:To compare the clinical efficacy of posterior C2-3 fixation combined with the bucking bar technique and posterior C2-3 fixation alone in the treatment of unstable Hangman fractures. METHODS:The clinical and imaging data of 55 patients with unstable Hangman fractures who underwent posterior C2-3 internal fixation in Affiliated Hospital of Southwest Medical University were retrospectively analyzed.According to the surgical plan,the patients were divided into two groups.Among them,23 patients received posterior cervical C2-3 internal fixation combined with the bucking bar technique(group A),and 32 patients received simple posterior C2-3 internal fixation(group B).Operation time,intraoperative blood loss,complications,pain visual analog scale score,neck disability index,American Spinal Injury Association classification,and patient satisfaction(Odom's classification)preoperation and during follow-up were compared between the two groups.The changes in C2-3 displacement and angulation and other imaging indicators were compared at each observation time point. RESULTS AND CONCLUSION:(1)There was no statistically significant difference in operation time,intraoperative blood loss,and postoperative complications between the two groups(P>0.05).(2)The neck pain visual analog scale and neck disability index scores of the two groups of patients at the final follow-up were significantly improved compared with those before surgery(P<0.05).The Odom standard classification showed that 21 cases(91%)in group A were excellent and 29 cases(91%)were excellent and good in group B.There was no statistically significant difference in the clinical efficacy indicators between the two groups(all P>0.05).(3)There was no significant difference in C2-3 angulation and displacement between the two groups before operation(P>0.05).Postoperation and at the last follow-up,the angle and displacement of C2-3 in both groups were significantly smaller than before surgery,and the difference was statistically significant(P<0.01).There was no statistically significant difference in the above indicators after surgery and at the last follow-up(P>0.05).After surgery and at the last follow-up,the displacement and angle of C2-3 in group A were significantly smaller than those in group B(P<0.05).(4)At the last follow-up,no patients in group A had residual deformity,and 4 cases(13%,4/32)in group B had residual deformity.(5)Therefore,posterior C2-3 fixation combined with transoral bucking bar technology may be beneficial to the reduction and stabilization of the vertebral body,reduces malunion,and can achieve better reduction.
8.Characteristic Expression of Multiple Neurotransmitters Oscillation Imbabance in Brains of 1 028 Patients with Depression
Anqi WANG ; Xuemei QING ; Yanshu PAN ; Pingfa ZHANG ; Ying ZHANG ; Jian LI ; Cheng ZHANG
Chinese Journal of Experimental Traditional Medical Formulae 2025;31(11):278-286
ObjectiveTo analyze the characteristic expression patterns of six neurotransmitters including 5-hydroxytryptamine (5-HT), dopamine (DA), acetylcholine (ACh), norepinephrine (NE), inhibitory neurotransmitter (INH), and excitatory neurotransmitter (EXC) in the whole brain and different brain regions of depression patients by Search of Encephalo Telex (SET), providing new ideas for the study of heterogeneous etiology of depression. Methods(1) A retrospective study was conducted on supra-slow signals of EEG fluctuations in 1 028 patients with depression. The SET system was used to obtain the expression information of six neurotransmitters in the whole brain and 12 brain regions: left frontal region (F3), right frontal region (F4), left central region (C3), right central region (C4), left parietal region (P3), right parietal region (P4), left occipital region (O1), right occipital region (O2), left anterior temporal region (F7), right anterior temporal region (F8), left posterior temporal region (T5), and right posterior temporal region (T6). The expression information of each neurotransmitter was compared with the normal model, and it was found that single neurotransmitter was in one of three states: increased, decreased, or normal expression. The simultaneous expression states of six neurotransmitters in the brain space were referred to as the expression pattern of multiple neurotransmitters. (2) A MySQL database was established to analyze the actual expression patterns of different neurotransmitters in the whole brain of patients with depression. (3) Factor analysis was conducted to further analyze the characteristic rules of 78 variables of neurotransmitters in the whole brain and 12 brain regions in depression patients. Results(1) The expression of single neurotransmitters in the whole brain and different brain regions of the total depression population showed one of three expression states (increased/decreased/normal), being normal in the majority. The decreased and increased expression of 5-HT, ACh, DA, INH, EXC, and NE in the whole brain occurred in 6% and 25%, 31% and 17%, 36% and 9%, 15% and 31%, 32% and 14%, and 22% and 22%, respectively. (2) The antagonizing pairs of neurotransmitters (EXC/INH, DA/5-HT, and ACh/NE) showed significant antagonistic relationships in the whole brain and different brain regions, with a strong negative correlation between EXC and INH (P<0.01, |r| values ranging from 0.69 to 0.76), a strong negative correlation between DA and 5-HT (P<0.01, |r| values ranging from 0.83 to 0.90), and a moderate negative correlation between ACh and NE (P<0.01, with |r| values ranging from 0.56 to 0.66). Meanwhile, non-antagonizing pairs of neurotransmitters in the whole brain and different brain regions also showed correlations, with DA/NE (P<0.01, |r| values ranging from 0.38 to 0.46) and NE/EXC (P<0.01, |r| values ranging from 0.56 to 0.61) showing weak and moderate negative correlations, respectively, and DA/EXC showing a weak positive correlation (P<0.01, |r| values ranging from 0.38 to 0.47). (3) The six neurotransmitters in the 1 028 patients with depression presented a total of 170 expression patterns in the whole brain. The top 30 expression patterns were reported in this paper, with a cumulative rate of 60.60%, including patterns ① INH+/5-HT-/ACh+/DA+/NE-/EXC- (9.05%), ② INH+/5-HT-/ACh↓/DA+/NE-/EXC- (4.57%), and ③ INH+/5-HT-/ACh+/DA+/NE↓/EXC- (3.31%). That is, the proportion of depression patients with normal levels of all the six neurotransmitters was 9.05%, and the patients with at least one neurotransmitter abnormality accounted for 91.95%. (4) The factor analysis extracted 22 common factors from 78 variables in the whole brain and different brain regions. These common factors showed the absolute values of loadings ranging from 0.32 to 0.86 and the eigenvalues (F) ranging from 1.03 to 13.43, with a cumulative contribution rate of 76.82%. The characteristic expression patterns included ① AChP3↓/AChW↓/AChC3↓/AChF3↓/AChO1↓/AChT5↓/AChF7↓/NEP3↑/NEW↑/NEC3↑/NEF3↑/NEO1↑/NET5↑/NEF7↑ (F=13.43, whole brain), ② 5-HTO2↑/DAO2↓/5-HTP4↑/DAP4↓/5-HTW↑/DAW↓/5-HTC4↑/DAC4↓ (F=5.94), and ③ EXCF4↓/DAF4↓/NEF4↑/INHF4↑/5-HTF4↑/AChF4↓ (F=5.33). ConclusionThe actual 170 expression patterns of 6 neurotransmitters in the whole brain of 1 028 depression patients indicate that depression is a heterogeneous disease with individualized characteristics. The 22 characteristic expression patterns in the whole brain and 12 brain regions verify the pathogenesis hypothesis of multi-neurotransmitters oscillation imbalance in brains of depression patients. In summary, this study provides new guidance for the etiology, diagnosis, and treatment of depression and establishes a methodological foundation for the effectiveness evaluation of individualized treatment of depression by traditional Chinese medicine based on the objective biological markers.
9.Characteristic Expression of Multiple Neurotransmitters Oscillation Imbabance in Brains of 1 028 Patients with Depression
Anqi WANG ; Xuemei QING ; Yanshu PAN ; Pingfa ZHANG ; Ying ZHANG ; Jian LI ; Cheng ZHANG
Chinese Journal of Experimental Traditional Medical Formulae 2025;31(11):278-286
ObjectiveTo analyze the characteristic expression patterns of six neurotransmitters including 5-hydroxytryptamine (5-HT), dopamine (DA), acetylcholine (ACh), norepinephrine (NE), inhibitory neurotransmitter (INH), and excitatory neurotransmitter (EXC) in the whole brain and different brain regions of depression patients by Search of Encephalo Telex (SET), providing new ideas for the study of heterogeneous etiology of depression. Methods(1) A retrospective study was conducted on supra-slow signals of EEG fluctuations in 1 028 patients with depression. The SET system was used to obtain the expression information of six neurotransmitters in the whole brain and 12 brain regions: left frontal region (F3), right frontal region (F4), left central region (C3), right central region (C4), left parietal region (P3), right parietal region (P4), left occipital region (O1), right occipital region (O2), left anterior temporal region (F7), right anterior temporal region (F8), left posterior temporal region (T5), and right posterior temporal region (T6). The expression information of each neurotransmitter was compared with the normal model, and it was found that single neurotransmitter was in one of three states: increased, decreased, or normal expression. The simultaneous expression states of six neurotransmitters in the brain space were referred to as the expression pattern of multiple neurotransmitters. (2) A MySQL database was established to analyze the actual expression patterns of different neurotransmitters in the whole brain of patients with depression. (3) Factor analysis was conducted to further analyze the characteristic rules of 78 variables of neurotransmitters in the whole brain and 12 brain regions in depression patients. Results(1) The expression of single neurotransmitters in the whole brain and different brain regions of the total depression population showed one of three expression states (increased/decreased/normal), being normal in the majority. The decreased and increased expression of 5-HT, ACh, DA, INH, EXC, and NE in the whole brain occurred in 6% and 25%, 31% and 17%, 36% and 9%, 15% and 31%, 32% and 14%, and 22% and 22%, respectively. (2) The antagonizing pairs of neurotransmitters (EXC/INH, DA/5-HT, and ACh/NE) showed significant antagonistic relationships in the whole brain and different brain regions, with a strong negative correlation between EXC and INH (P<0.01, |r| values ranging from 0.69 to 0.76), a strong negative correlation between DA and 5-HT (P<0.01, |r| values ranging from 0.83 to 0.90), and a moderate negative correlation between ACh and NE (P<0.01, with |r| values ranging from 0.56 to 0.66). Meanwhile, non-antagonizing pairs of neurotransmitters in the whole brain and different brain regions also showed correlations, with DA/NE (P<0.01, |r| values ranging from 0.38 to 0.46) and NE/EXC (P<0.01, |r| values ranging from 0.56 to 0.61) showing weak and moderate negative correlations, respectively, and DA/EXC showing a weak positive correlation (P<0.01, |r| values ranging from 0.38 to 0.47). (3) The six neurotransmitters in the 1 028 patients with depression presented a total of 170 expression patterns in the whole brain. The top 30 expression patterns were reported in this paper, with a cumulative rate of 60.60%, including patterns ① INH+/5-HT-/ACh+/DA+/NE-/EXC- (9.05%), ② INH+/5-HT-/ACh↓/DA+/NE-/EXC- (4.57%), and ③ INH+/5-HT-/ACh+/DA+/NE↓/EXC- (3.31%). That is, the proportion of depression patients with normal levels of all the six neurotransmitters was 9.05%, and the patients with at least one neurotransmitter abnormality accounted for 91.95%. (4) The factor analysis extracted 22 common factors from 78 variables in the whole brain and different brain regions. These common factors showed the absolute values of loadings ranging from 0.32 to 0.86 and the eigenvalues (F) ranging from 1.03 to 13.43, with a cumulative contribution rate of 76.82%. The characteristic expression patterns included ① AChP3↓/AChW↓/AChC3↓/AChF3↓/AChO1↓/AChT5↓/AChF7↓/NEP3↑/NEW↑/NEC3↑/NEF3↑/NEO1↑/NET5↑/NEF7↑ (F=13.43, whole brain), ② 5-HTO2↑/DAO2↓/5-HTP4↑/DAP4↓/5-HTW↑/DAW↓/5-HTC4↑/DAC4↓ (F=5.94), and ③ EXCF4↓/DAF4↓/NEF4↑/INHF4↑/5-HTF4↑/AChF4↓ (F=5.33). ConclusionThe actual 170 expression patterns of 6 neurotransmitters in the whole brain of 1 028 depression patients indicate that depression is a heterogeneous disease with individualized characteristics. The 22 characteristic expression patterns in the whole brain and 12 brain regions verify the pathogenesis hypothesis of multi-neurotransmitters oscillation imbalance in brains of depression patients. In summary, this study provides new guidance for the etiology, diagnosis, and treatment of depression and establishes a methodological foundation for the effectiveness evaluation of individualized treatment of depression by traditional Chinese medicine based on the objective biological markers.
10.Junctophilin-2 MORN-Helix Domain: Structural Basis for Membrane Binding and Hypertrophic Cardiomyopathy-associated Mutations
Jing-Xin WANG ; Zhi-Wei LI ; Wei LIU ; Wen-Qing ZHANG ; Jian-Chao LI
Progress in Biochemistry and Biophysics 2025;52(8):2103-2116
ObjectiveJunctophilin-2 (JPH2) is an essential structural protein that maintains junctional membrane complexes (JMCs) in cardiomyocytes by tethering the plasma membrane to the sarcoplasmic reticulum, thereby facilitating excitation-contraction (E-C) coupling. Mutations in JPH2 have been associated with hypertrophic cardiomyopathy (HCM), but the molecular mechanisms governing its membrane-binding properties and the functional relevance of its membrane occupation and recognition nexus (MORN) repeat motifs remain incompletely understood. This study aimed to elucidate the structural basis of JPH2 membrane association and its implications for HCM pathogenesis. MethodsA recombinant N-terminal fragment of mouse JPH2 (residues1-440), encompassing the MORN repeats and an adjacent helical region, was purified under near-physiological buffer conditions.X-ray crystallography was employed to determine the structure of the JPH2 MORN-Helix domain. Sequence conservation analysis across species and junctophilin isoforms was performed to assess the evolutionary conservation of key structural features. Functional membrane-binding assays were conducted using liposome co-sedimentation and cell-based localization studies in COS7 and HeLa cells. In addition, site-directed mutagenesis targeting positively charged residues and known HCM-associated mutations, including R347C, was used to evaluate their effects on membrane interaction and subcellular localization. ResultsThe crystal structure of the mouse JPH2 MORN-Helix domain was resolved at 2.6 Å, revealing a compact, elongated architecture consisting of multiple tandem MORN motifs arranged in a curved configuration, forming a continuous hydrophobic core stabilized by alternating aromatic residues. A C-terminal α-helix further reinforced structural integrity. Conservation analysis identified the inner groove of the MORN array as a highly conserved surface, suggesting its role as a protein-binding interface. A flexible linker segment enriched in positively charged residues, located adjacent to the MORN motifs, was found to mediate direct electrostatic interactions with negatively charged phospholipid membranes. Functional assays demonstrated that mutation of these basic residues impaired membrane association, while the HCM-linked R347C mutation completely abolished membrane localization in cellular assays, despite preserving the overall MORN-Helix fold in structural modeling. ConclusionThis study provides structural insight into the membrane-binding mechanism of the cardiomyocyte-specific protein JPH2, highlighting the dual roles of its MORN-Helix domain in membrane anchoring and protein interactions. The findings clarify the structural basis for membrane targeting via a positively charged linker and demonstrate that disruption of this interaction—such as that caused by the R347C mutation—likely contributes to HCM pathogenesis. These results not only enhance current understanding of JPH2 function in cardiac E-C coupling but also offer a structural framework for future investigations into the assembly and regulation of JMCs in both physiological and disease contexts.

Result Analysis
Print
Save
E-mail