Membrane proteins are integral components of cellular membranes, accounting for approximately 30% of the mammalian proteome and serving as targets for 60% of FDA-approved drugs. They are critical to both physiological functions and disease mechanisms. Their functional protein-protein interactions form the basis for many physiological processes, such as signal transduction, material transport, and cell communication. Membrane protein interactions are characterized by membrane environment dependence, spatial asymmetry, weak interaction strength, high dynamics, and a variety of interaction sites. Therefore, in situ analysis is essential for revealing the structural basis and kinetics of these proteins. This paper introduces currently available in situ analytical techniques for studying membrane protein interactions and evaluates the characteristics of each. These techniques are divided into two categories: label-based techniques (e.g., co-immunoprecipitation, proximity ligation assay, bimolecular fluorescence complementation, resonance energy transfer, and proximity labeling) and label-free techniques (e.g., cryo-electron tomography, in situ cross-linking mass spectrometry, Raman spectroscopy, electron paramagnetic resonance, nuclear magnetic resonance, and structure prediction tools). Each technique is critically assessed in terms of its historical development, strengths, and limitations. Based on the authors’ relevant research, the paper further discusses the key issues and trends in the application of these techniques, providing valuable references for the field of membrane protein research. Label-based techniques rely on molecular tags or antibodies to detect proximity or interactions, offering high specificity and adaptability for dynamic studies. For instance, proximity ligation assay combines the specificity of antibodies with the sensitivity of PCR amplification, while proximity labeling enables spatial mapping of interactomes. Conversely, label-free techniques, such as cryo-electron tomography, provide near-native structural insights, and Raman spectroscopy directly probes molecular interactions without perturbing the membrane environment. Despite advancements, these methods face several universal challenges: (1) indirect detection, relying on proximity or tagged proxies rather than direct interaction measurement; (2) limited capacity for continuous dynamic monitoring in live cells; and (3) potential artificial influences introduced by labeling or sample preparation, which may alter native conformations. Emerging trends emphasize the multimodal integration of complementary techniques to overcome individual limitations. For example, combining in situ cross-linking mass spectrometry with proximity labeling enhances both spatial resolution and interaction coverage, enabling high-throughput subcellular interactome mapping. Similarly, coupling fluorescence resonance energy transfer with nuclear magnetic resonance and artificial intelligence (AI) simulations integrates dynamic structural data, atomic-level details, and predictive modeling for holistic insights. Advances in AI, exemplified by AlphaFold’s ability to predict interaction interfaces, further augment experimental data, accelerating structure-function analyses. Future developments in cryo-electron microscopy, super-resolution imaging, and machine learning are poised to refine spatiotemporal resolution and scalability. In conclusion, in situ analysis of membrane protein interactions remains indispensable for deciphering their roles in health and disease. While current technologies have significantly advanced our understanding, persistent gaps highlight the need for innovative, integrative approaches. By synergizing experimental and computational tools, researchers can achieve multiscale, real-time, and perturbation-free analyses, ultimately unraveling the dynamic complexity of membrane protein networks and driving therapeutic discovery.

Aim To investigate the role of metabolites of eicosapentaenoic acid (EPA) in promoting the transdifferentiation of pancreatic α cells to β cells. Methods Male C57BL/6J mice were injected intraperitoneally with 60 mg/kg streptozocin (STZ) for five consecutive days to establish a type 1 diabetes (T1DM) mouse model. After two weeks, they were randomly divided into model groups and 97% EPA diet intervention group, 75% fish oil (50% EPA +25% DHA) diet intervention group, and random blood glucose was detected every week; after the model expired, the regeneration of pancreatic β cells in mouse pancreas was observed by immunofluorescence staining. The islets of mice (obtained by crossing GCG

Objective To explore the value of MR diffusion tensor imaging(DTI)in evaluating the effect of march training on the thigh muscles of recruits.Methods DTI scans of the right thigh were performed three times in forty recruits:before and after the march training and one month after the rest.Fractional anisotropy(FA)was measured on the cross-sectional images of the thigh muscles,including rectus femoris(RF),vastus medialis(VM),vastus lateralis(VL),vastus intermedius(VI),gracilis muscle(GM),sartorius muscle(SM),semitendinosus muscle(STM),semimembranosus muscle(SMM),long head of biceps femoris(LHBF)and short head of biceps femoris(SHBF).The percentage changes in FA values of each muscle after the training and rest were calculated.Paired samplet-tests were used to analyze the differences in FA among the thigh muscles at different time points,and one-way ANOVA was used to analyze the differences in the percentage changes of FA among the thigh muscles after the training and rest.Results Compared to pre-training,the FA values of all thigh muscles significantly decreased after the training,with statistical differences(P＜0.05).After the rest,the FA values of all thigh muscles recovered,but statistical differences remained in RF(P＜0.001),VM(P＜0.001),VL(P=0.001),STM(P=0.046),and LHBF(P=0.013).After the training and rest,the FA values of the recruits'thigh muscles showed a"decreasing first and then increasing"trend.There were statistical differences in the percentage changes of FA after the training and the recovery percentages of FA after the rest among the thigh muscles(P＜0.001,P＜0.001).Conclusion DTI may reflect the ultra-structure changes in the thigh muscles of recruits after the march training and provide a quantitative and noninvasive assessment of muscle micro-injuries.

This study was aimed at understanding the genomic characteristics of the Vibrio cholerae O1 group isolated from humans in Fujian Province,to provide essential data for the molecular epidemiological study of cholera.From 2008 to 2022,16 strains of the V.cholerae O1 group from patients and carriers were collected,and antibiotic sensitivity was determined accord-ing to the minimum inhibitory concentration(MIC).The whole genome sequences obtained through second generation sequen-cing were analyzed in open source software,including snippy,Roary,and Prokka,as well as online analysis websites,inclu-ding NCBI and BacWGSTdb,for core-genome multilocus sequence typing(cgMLST),core-genome single nucleotide polymor-phism analysis(cgSNP),virulence gene analysis,drug resistance gene prediction,and pan-genomic diversity analysis.The whole genome sequences of V.cholerae were divided into five sequence types(STs),among which the newly discovered ST182 and ST1480 were the evolutionary branches of the current dominant clonal group ST75 in China,and were highly related to two strains isolated from Taiwan in 2010 and 2013,respectively.Both toxigenic strains and non-toxigenic strains carried a variety of virulence factors and showed gene variation to varying degrees.Thirteen drug resistance genes in seven categories were predicted,among which the distribution of colistin and tetracycline resistance genes was consistent with the drug resistance phenotype.Pan-ge-nomic analysis indicated that V.cholerae had an open pan-genome,and Roary cluster analysis showed higher resolution than cgMLST.In summary,V.cholerae O1 group isolates from humans in Fujian Province have polymorphisms in genome structure and function,and the newly discovered ST1480 clone group has epidemic potential.Therefore,the monitoring of such strains must be strengthened.

Objective:To investigate the effect of TLK2 expression regulated by miR-21 on proliferation and apoptosis of acute myeloid leukemia cells.Methods:Seventy patients with AML admitted to our hospital from January 2019 to July 2022 were selected,while 30 patients with iron deficiency anemia were selected as the control group.Bone marrow mononuclear cells(BMMNCs)of the patients were obtained using Ficoll density gradient centrifugation.RT-qPCR was used to determine the expression levels of miR-21 and TLK2 mRNA in BMMNCs.Mimics-miR-21,mimics-NC,inhibitor-miR-21,inhibitor-NC and NC were transfected into HL-60 cells using liposome-mediated transfection technology.CCK-8 method was used to determine the activity of transfected HL-60 cells after treatment with cytarabine.The apoptosis rate of HL-60 transfected cells was determined by TUNEL method.The expression of TLK2 mRNA in HL-60 cells transfected with inhibitor-miR-21 was determined by RT-qPCR.Results:The relative expression levels of miR-21 and TLK2 mRNA in BMMNCs of AML patients were significantly higher than those of controls(both P＜0.05).After HL-60 cells were treated with cytarabine,both the cell activity of inhibitor-miR-21 group and mimics-miR-21 group decreased significantly with the increase of cytarabine concentration(both P＜0.05).However,at each concentration point of cytarabine,the cell activity of inhibitor-miR-21 group was lower than that of control group(P＜0.05),while mimics-miR-21 group was higher than control group(P＜0.05).After HL-60 cells were treated with cytarabine,the apoptosis rate of inhibitor-miR-21 group was significantly increased(P＜0.05),while that of mimics-miR-21 group was significantly decreased(P＜0.05).After HL-60 cells were treated with inhibitor-miR-21,the relative expression of TLK2 mRNA decreased significantly(P＜0.05).Conclusion:miR-21 is highly expressed in AML patients,which may promote the apoptosis of AML cells by inhibiting the expression of TLK2.

Objective:To investigate the protective effect of endogenous ω-3 polyunsaturated fatty acid(PUFA)against cisplatin-induced myelosuppression and the mechanism of reducing apoptosis in bone marrow nucleated cells using mfat-1 transgenic mice.Methods:The experimental animals were divided into 4 groups:wild-type mice normal control group,mfat-1 transgenic mice normal control group,wild-type mice model group and mfat-1 transgenic mice model group.The mice in the model group were injected intraperitoneally with 7.5 mg/kg cisplatin on day 0 and day 7 to construct a myelosuppression model,while the mice in the normal control group were injected intraperitoneally with an equal amount of saline,and their status was observed and their body weight was measured daily.Peripheral blood was taken after 14 day for routine blood analysis,and the content and proportion of PUFA in peripheral blood were detected using gas chromatography.Bone marrow nucleated cells in the femur of mice were counted.The histopathological changes in bone marrow were observed by histopathological staining.The apoptosis of nucleated cells and the expression level changes of apoptosis-related genes in the bone marrow of mice were detected by flow cytometry and fluorescence quantitative PCR.Results:Compared with wild-type mice,mfat-1 transgenic mice showed significantly increased levels of ω-3 PUFA in peripheral blood and greater tolerance to cisplatin.Peripheral blood analysis showed that endogenous ω-3 PUFA promoted the recovery of leukocytes,erythrocytes,platelets and haemoglobin in peripheral blood of myelosuppressed mice.The results of HE staining showed that endogenous ω-3 PUFA significantly improved the structural damage of bone marrow tissue induced by cisplatin.Flow cytometry and PCR showed that,compared with wild-type mice model group,the apoptosis rate of bone marrow nucleated cells in mfat-1 transgenic mice was significantly reduced(P＜0.001),and the expression of anti-apoptotic genes Bcl-2 mRNA was significantly increased(P＜0.01),while the expressions of pro-apoptotic genes Bax and Bak mRNA were significantly reduced(P＜0.001,P＜0.05).Conclusion:Endogenous ω-3 PUFA can reduce cisplatin-induced apoptosis in bone marrow nucleated cells,increase the number of peripheral blood cells and exert a protective effect against cisplatin-induced myelosuppression by regulating the expression of apoptosis-related genes.

Objective To explore the risk factors associated with cow's milk protein allergy(CMPA)in infants.Methods This study was a multicenter prospective nested case-control study conducted in seven medical centers in Beijing,China.Infants aged 0-12 months were included,with 200 cases of CMPA infants and 799 control infants without CMPA.Univariate and multivariate logistic regression analyses were used to investigate the risk factors for the occurrence of CMPA.Results Univariate logistic regression analysis showed that preterm birth,low birth weight,birth from the first pregnancy,firstborn,spring birth,summer birth,mixed/artificial feeding,and parental history of allergic diseases were associated with an increased risk of CMPA in infants(P＜0.05).Multivariate logistic regression analysis revealed that firstborn(OR=1.89,95％CI:1.14-3.13),spring birth(OR=3.42,95％CI:1.70-6.58),summer birth(OR=2.29,95％CI:1.22-4.27),mixed/artificial feeding(OR=1.57,95％CI:1.10-2.26),parental history of allergies(OR=2.13,95％CI:1.51-3.02),and both parents having allergies(OR=3.15,95％CI:1.78-5.56)were risk factors for CMPA in infants(P＜0.05).Conclusions Firstborn,spring birth,summer birth,mixed/artificial feeding,and a family history of allergies are associated with an increased risk of CMPA in infants.[Chinese Journal of Contemporary Pediatrics,2024,26(3):230-235]

Objective To design a novel oxygenator to solve the existing problems of extracorporeal membrane oxygenation(ECMO)machine in high transmembrane pressure difference,low efficiency of blood oxygen exchange and susceptibility to thrombosis.Methods The main body of the oxygenator vascular access flow field was gifted with a flat cylindrical shape.The topology of the vascular access was modeled in three dimensions,and the whole flow field was cut into a blood inlet section,an inlet buffer,a heat exchange zone,a blood oxygen exchange zone,an outlet buffer and a blood outlet section.The oxygenator was compared with Quadrox oxygenator by means of ANSYS FLUENT-based simulation and prototype experiments.Results Simulation calculations showed the oxygenator designed was comparable to the clinically used ones in general,and gained advantages in transmembrane pressure difference,blood oxygen exchange and flow uniformity.Experimental results indicated that the oxygenator behaved better than Quadrox oxygenator in transmembrane pressure difference and blood oxygen exchange.Conclusion The oxygenator has advantages in transmem-brane pressure difference,temperature change,blood oxygen ex-change and low probability of thrombosis.[Chinese Medical Equipment Journal,2024,45(3):23-28]

The anti-apoptotic members of Bcl-2 family proteins, Bcl-2 and Mcl-1, are considered therapeutic targets of various cancers. In this article, we developed four hydrophobic tag (HyT)-based protein degraders of Bcl-2/Mcl-1, based on a Bcl-2/Mcl-1 dual inhibitor S1-6, and tested their capability in Bcl-2/Mcl-1 degradation and apoptotic induction in MCF-7 cells. Interestingly, different linkers in the HyT degraders led to selective Bcl-2/Mcl-1 degradation, though the degraders S1-D1-S1-D4 maintained the pan-Bcl-2 family binding capacity. Among them, S1-D2 and S1-D4, two compounds bearing a hydrophobic linker or a PEG linker, were observed to potently and selectively induce the ubiquitination and proteasomal degradation of Bcl-2 and Mcl-1 in living cells, with a degradation rate of more than 80% or 60%, respectively. Moreover, the HyT-based degraders showed increased lethality of cancer cells compared to the parent inhibitor S1-6, demonstrating that the advantage of degraders to the occupancy-based inhibitors.

This study aimed to analyze the effect of matrine on tumor necrosis factor-α(TNF-α)-induced inflammatory response in human umbilical vein endothelial cells(HUVECs) and explore whether the underlying mechanism was related to the miR-25-3p-mediated Krüppel-like factor 4(Klf4) pathway. The HUVEC cell inflammation model was induced by TNF-α stimulation. After 24 or 48 hours of incubation with different concentrations of matrine(0.625, 1.25, and 2.5 mmol·L~(-1)), CCK-8 assay was used to detect cell proliferation. After treatment with 2.5 mmol·L~(-1) matrine for 48 h, the expression of TNF-α, interleukin-6(IL-6), interleukin-1β(IL-1β), and Klf4 mRNA and miR-25-3p was detected by real-time fluorescence-based quantitative PCR, and the protein expression of TNF-α, IL-6, IL-1β, and Klf4 was detected by Western blot. The anti-miR-25-3p was transfected into HUVECs, and the effect of anti-miR-25-3p on TNF-α-induced cell proliferation and inflammatory factors was detected by the above method. The cells were further transfected with miR-25-3p and incubated with matrine to detect the changes in proliferation and expression of related inflammatory factors, miR-25-3p, and Klf4. The targeting relationship between miR-25-3p and Klf4 was verified by bioinformatics analysis and dual luciferase reporter gene assay. The results displayed that matrine could inhibit TNF-α-induced HUVEC proliferation, decrease the mRNA and protein expression of TNF-α, IL-6, and IL-1β, increase the mRNA and protein expression of Klf4, and reduce the expression of miR-25-3p. Bioinformatics analysis showed that there were specific complementary binding sites between miR-25-3p and Klf4 sequences. Dual luciferase reporter gene assay confirmed that miR-25-3p negatively regulated Klf4 expression in HUVECs by targeting. The inhibition of miR-25-3p expression can reduce TNF-α-induced cell proliferation and mRNA and protein expression of TNF-α, IL-6, and IL-1β. MiR-25-3p overexpression could reverse the effect of matrine on TNF-α-induced cell proliferation and the mRNA and protein expression of TNF-α, IL-6, IL-1β, and Klf4. This study shows that matrine inhibits the inflammatory response induced by TNF-α in HUVECs through miR-25-3p-mediated Klf4 pathway.
Humans ; Tumor Necrosis Factor-alpha/metabolism* ; MicroRNAs/metabolism* ; Human Umbilical Vein Endothelial Cells ; Matrines ; Interleukin-6/genetics* ; Signal Transduction ; Antagomirs ; Inflammation/metabolism* ; Luciferases/pharmacology* ; RNA, Messenger ; Apoptosis