The timely and efficient repair of the plasma membrane in skeletal muscle cells following injury is critical for maintaining cellular function and tissue integrity. Extracellular vesicles (EVs) play a pivotal role in this process through multi-level mechanisms. This review systematically summarizes the generation, secretion, and multifunctional roles of EVs in the repair of skeletal muscle plasma membrane damage: (1) removing damaged membrane fragments and cellular debris via endocytosis and exocytosis to maintain plasma membrane stability; (2) fusing with the injured plasma membrane to supply essential components for membrane repair and restore membrane integrity; and (3) serving as a vital mediator of intercellular communication, transmitting repair signals, promoting intercellular interactions, and orchestrating multi-level responses to facilitate tissue regeneration and functional recovery. Additionally, this article explores the potential applications of EVs in the treatment of exercise-induced injuries and muscular diseases, aiming to provide theoretical insights and novel strategies for future research and EV-based therapeutic approaches.
Extracellular Vesicles/physiology* ; Humans ; Muscle, Skeletal/physiology* ; Cell Membrane/physiology* ; Animals ; Regeneration/physiology* ; Exocytosis/physiology* ; Endocytosis/physiology* ; Cell Communication/physiology*

This study aims to elucidate the role and mechanism of clematichinenoside AR(CAR) in protecting bone marrow mesenchymal stem cells(BMSCs) from hypoxia-induced apoptosis. BMSCs were isolated by the bone fragment method and identified by flow cytometry. Cells were cultured under normal conditions(37℃, 5% CO_2) and hypoxic conditions(37℃, 90% N_2, 5% CO_2) and treated with CAR. The BMSCs were classified into eight groups: control(normal conditions), CAR(normal conditions + CAR), hypoxia 24 h, hypoxia 24 h + CAR, hypoxia 48 h, hypoxia 48 h + CAR, hypoxia 72 h, and hypoxia 72 h + CAR. The cell counting kit-8(CCK-8) assay and terminal-deoxynucleoitidyl transferase mediated nick end labeling(TUNEL) were employed to measure cell proliferation and apoptosis, respectively. The number of mitochondria and mitochondrial membrane potential were measured by MitoTracker®Red CM-H2XRo staining and JC-1 staining, respectively. The level of reactive oxygen species(ROS) was measured with the DCFH-DA fluorescence probe. The protein levels of B-cell lymphoma-2 associated X protein(BAX), caspase-3, and optic atrophy 1(OPA1) were determined by Western blot. The results demonstrated that CAR significantly increased cell proliferation. Compared with the control group, the hypoxia groups showed increased apoptosis rates, reduced mitochondria, elevated ROS levels, decreased mitochondrial membrane potential, upregulated expression of BAX and caspase-3, and downregulated expression of OPA1. In comparison to the corresponding hypoxia groups, CAR intervention significantly decreased the apoptosis rate, increased mitochondria, reduced ROS levels, elevated mitochondrial membrane potential, downregulated the expression of BAX and caspase-3, and upregulated the expression of OPA1. Therefore, it can be concluded that CAR may exert an anti-apoptotic effect on BMSCs under hypoxic conditions by regulating OPA1 to maintain mitochondrial homeostasis.
Mesenchymal Stem Cells/metabolism* ; Apoptosis/drug effects* ; Mitochondria/metabolism* ; Animals ; Rats ; Cell Hypoxia/drug effects* ; Homeostasis/drug effects* ; Reactive Oxygen Species/metabolism* ; Rats, Sprague-Dawley ; Membrane Potential, Mitochondrial/drug effects* ; Saponins/pharmacology* ; Caspase 3/genetics* ; Male ; bcl-2-Associated X Protein/genetics* ; Bone Marrow Cells/metabolism* ; Cell Proliferation/drug effects* ; Protective Agents/pharmacology* ; Cells, Cultured

This paper explored the specific mechanism of ginsenoside Rg_1 in regulating mitochondrial fusion through the neurogenic gene Notch homologous protein 1(Notch1) pathway to alleviate hypoxia/reoxygenation(H/R) injury in HL-1 cells. The relative viability of HL-1 cells after six hours of hypoxia and two hours of reoxygenation was detected by cell counting kit-8(CCK-8). The lactate dehydrogenase(LDH) activity in the cell supernatant was detected by the lactate substrate method. The content of adenosine triphosphate(ATP) was detected by the luciferin method. Fluorescence probes were used to detect intracellular reactive oxygen species(Cyto-ROS) levels and mitochondrial membrane potential(ΔΨ_m). Mito-Tracker and Actin were co-imaged to detect the number of mitochondria in cells. Fluorescence quantitative polymerase chain reaction and Western blot were used to detect the mRNA and protein expression levels of Notch1, mitochondrial fusion protein 2(Mfn2), and mitochondrial fusion protein 1(Mfn1). The results showed that compared with that of the control group, the cell activity of the model group decreased, and the LDH released into the cell culture supernatant increased. The level of Cyto-ROS increased, and the content of ATP decreased. Compared with that of the model group, the cell activity of the ginsenoside Rg_1 group increased, and the LDH released into the cell culture supernatant decreased. The level of Cyto-ROS decreased, and the ATP content increased. Ginsenoside Rg_1 elevated ΔΨ_m and increased mitochondrial quantity in HL-1 cells with H/R injury and had good protection for mitochondria. After H/R injury, the mRNA and protein expression levels of Notch1 and Mfn1 decreased, while the mRNA and protein expression levels of Mfn2 increased. Ginsenoside Rg_1 increased the mRNA and protein levels of Notch1 and Mfn1, and decreased the mRNA and protein levels of Mfn2. Silencing Notch1 inhibited the action of ginsenoside Rg_1, decreased the mRNA and protein levels of Notch1 and Mfn1, and increased the mRNA and protein levels of Mfn2. In summary, ginsenoside Rg_1 regulated mitochondrial fusion through the Notch1 pathway to alleviate H/R injury in HL-1 cells.
Ginsenosides/pharmacology* ; Receptor, Notch1/genetics* ; Signal Transduction/drug effects* ; Mice ; Animals ; Mitochondrial Dynamics/drug effects* ; Mitochondria/metabolism* ; Cell Line ; Reactive Oxygen Species/metabolism* ; Oxygen/metabolism* ; Cell Hypoxia/drug effects* ; Cell Survival/drug effects* ; Membrane Potential, Mitochondrial/drug effects* ; Humans

This study investigates the effect of glycyrrhetinic acid(GA) combined with doxorubicin(DOX) on apoptosis in HepG2 cells and its possible mechanisms. HepG2 cells were cultured in vitro, and cell viability was assessed using the cell counting kit-8(CCK-8) method. Flow cytometry was used to measure apoptosis levels in HepG2 cells. The cells were divided into the following groups: control group(0 μmol·L~(-1)), DOX group(2 μmol·L~(-1)), GA group(150 μmol·L~(-1)), and DOX + GA combination group(2 μmol·L~(-1) DOX + 150 μmol·L~(-1) GA), with treatments given for 24 hours. The colocalization level between the endoplasmic reticulum(ER) and mitochondria was assessed by colocalization fluorescence imaging. Fluorescence probes were used to measure the Ca~(2+) content in the ER and mitochondria. The qRT-PCR and Western blot were used to determine the mRNA and protein expression of sirtuin-3(SIRT3). Co-immunoprecipitation(CO-IP) was applied to investigate the interactions between voltage-dependent anion channel 1(VDAC1) and SIRT3, as well as between VDAC1, glucose-regulated protein 75(GRP75), and inositol 1,4,5-trisphosphate receptor(IP3R). The results showed that the combination of DOX and GA promoted apoptosis in HepG2 liver cancer cells. The colocalization level between the ER and mitochondria was significantly reduced, the Ca~(2+) content in the ER was significantly increased, and the Ca~(2+) content in the mitochondria was significantly decreased. The relative expression of VDAC1, GRP75, and IP3R was significantly reduced, and interactions between VDAC1, GRP75, and IP3R were observed. SIRT3 mRNA and protein expression levels were significantly increased, and an interaction between SIRT3 and VDAC1 was detected. The acetylation level of VDAC1 was significantly decreased. In conclusion, GA combined with DOX induces apoptosis in HepG2 cells by mediating the deacetylation of VDAC1 through SIRT3, weakening the interactions among VDAC1, GRP75, and IP3R. This regulates the formation of endoplasmic reticulum-mitochondrial membrane domains(ERMMDs), affects Ca~(2+) transport between the ER and mitochondria, and ultimately triggers cell apoptosis.
Humans ; Apoptosis/drug effects* ; Hep G2 Cells ; Glycyrrhetinic Acid/pharmacology* ; Doxorubicin/pharmacology* ; Liver Neoplasms/genetics* ; Carcinoma, Hepatocellular/physiopathology* ; Mitochondria/metabolism* ; Endoplasmic Reticulum/metabolism* ; Cell Survival/drug effects* ; Membrane Proteins/genetics*

This study investigated the mechanism by which Jianpi Bushen Yiqi Decoction promotes acetylcholine receptor(AChR) clustering in myasthenia gravis through the Agrin/low-density lipoprotein receptor-related protein 4(LRP4)/muscle-specific receptor tyrosine kinases(MuSK) signaling pathway. A total of 114 female C57BL/6J mice were divided into the normal group, modeling group, and solvent control group. The normal group and the solvent control group were immunized with phosphate-buffered saline(PBS), while the modeling group was established as an experimental autoimmune myasthenia gravis(EAMG) model using the murine-derived AChR-α subunit R97-116 peptide fragment. After successful modeling, the mice were randomly assigned to the model group, the low-, medium-, and high-dose Jianpi Bushen Yiqi Decoction groups, and the prednisone group. After four weeks of continuous treatment, muscle strength was assessed using Lennon scores and grip strength tests. Immunofluorescence staining was conducted on differentiated C2C12 myotubes incubated with a drug-containing serum to observe the number of AChR clusters. The integrity of AChR on myofilaments in mouse gastrocnemius muscles was further assessed by immunofluorescence staining. Hematoxylin-Eosin(HE)staining was applied to examine pathological changes in the gastrocnemius muscles of EAMG mice treated with Jianpi Bushen Yiqi Decoction. Western blot was utilized to detect the expression of key proteins in the Agrin/LRP4/MuSK signaling pathway in both C2C12 myotubes and mouse gastrocnemius muscles. The results demonstrated that compared to the model group, the prednisone group exhibited a significant decrease in the body weights of mice, whereas no significant differences in the body weights of mice were observed among the low-, medium-, and high-dose Jianpi Bushen Yiqi Decoction groups. All treatment groups showed significantly improved grip strength and Lennon scores. Additionally, the formula promoted AChR clustering on myotubes and enhanced AChR integrity in gastrocnemius myofilaments and reduced inflammatory infiltration between muscle tissue and fibrous hyperplasia. Furthermore, Jianpi Bushen Yiqi Decoction upregulated the protein expression of AChRα1, Agrin, and p-MuSK in C2C12 myotubes and increased the protein expression of AChRα1, Agrin, MuSK, p-MuSK, LRP4, and docking protein 7(Dok-7)in gastrocnemius tissue. In conclusion, Jianpi Bushen Yiqi Decoction may promote AChR clustering by targeting key proteins in the Agrin/LRP4/MuSK signaling pathway, thereby improving neuromuscular junction function and enhancing muscle strength.
Animals ; Agrin/genetics* ; Mice ; Drugs, Chinese Herbal/administration & dosage* ; Signal Transduction/drug effects* ; Receptors, Cholinergic/genetics* ; Female ; Mice, Inbred C57BL ; Receptor Protein-Tyrosine Kinases/genetics* ; Neuromuscular Junction/metabolism* ; Myasthenia Gravis, Autoimmune, Experimental/physiopathology* ; Humans ; LDL-Receptor Related Proteins

In this report, the protective effect and molecular mechanism of Chaihu Shugan San-containing serum on corticosterone(CORT)-induced mitochondrial damage in pheochromocytoma(PC12) cells was studied based on CORT-induced rat PC12 cell model. The cultured cells were divided into five groups: blank control group, CORT group(400 μmol·L~(-1) CORT), Chaihu Shugan San-containing serum group(400 μmol·L~(-1) CORT + 10% Chaihu Shugan San-containing serum), control serum group(400 μmol·L~(-1) CORT + 10% control serum), and fluoxetine group(400 μmol·L~(-1) CORT + 10% fluoxetine-containing serum). The study was carried out by cell activity detection, mitochondrial morphology observation, membrane potential measurement, energy metabolism analysis, and mitochondrial dynamics-related protein detection. The results showed that CORT treatment significantly reduced the survival rate of PC12 cells, altered mitochondrial morphology, and decreased mitochondrial membrane potential and adenosine triphosphate(ATP) synthetic rate. Both Chaihu Shugan San-and fluoxetine-containing serum significantly increased the survival rate of CORT-treated PC12 cells and the ATP synthetic rate in the mitochondria. Unlike fluoxetine, Chaihu Shugan San-containing serum significantly inhibited the decrease in mitochondrial membrane potential caused by CORT and increased the oxygen consumption rate(OCR) values of both mitochondrial maximum respiration and reserve respiration capacity. Western blot analysis showed that CORT induced upregulated protein expressions of dynamin-related protein 1(Drp1) and peroxisome proliferator-activated receptor gamma co-activator 1α(PGC-1α) in PC12 cells and specific protein expression of optic atrophy protein 1(OPA1), yet it repressed the protein expressions of silent information regulator 1(SIRT1) and mitochondrial fusion protein 1(Mfn1) in PC12 cells. Both Chaihu Shugan San-and fluoxetine-containing serum significantly inhibited the protein expression of Drp1. However, only Chaihu Shugan San-containing serum could significantly inhibit the CORT-induced upregulation protein of PGC-1α. RESULTS:: herein suggest that Chaihu Shugan San-containing serum can alleviate CORT-induced damage in PC12 cells, which may be related to the mitochondrial fragmentation/lipid peroxidation protection by Drp1 inhibition, as well as mitochondrial dynamics and energy metabolism mediated by PGC-1α/SIRT1 signaling pathway.
Animals ; PC12 Cells ; Rats ; Mitochondrial Dynamics/drug effects* ; Mitochondria/metabolism* ; Corticosterone/adverse effects* ; Membrane Potential, Mitochondrial/drug effects* ; Drugs, Chinese Herbal/pharmacology* ; Protective Agents/pharmacology* ; Cell Survival/drug effects*

OBJECTIVE: To investigate the effects of 4-methylcatechol (4MC) on the migration and inflammatory response in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS), as well as its underlying mechanisms of action. METHODS: RA-FLS was isolated from synovial tissue donated by RA patients, and the optimal concentration of 4MC was determined by cell counting kit 8 method for subsequent experiments, and the effect of 4MC on the migratory ability of RA-FLS was evaluated via a cell scratch assay. An inflammation model of RA-FLS was induced by tumor necrosis factor α (TNF-α). Real-time fluorescence quantitative PCR and ELISA were employed to detect the gene and protein expression levels of interleukin-1β (IL-1β) and IL-6 in RA-FLS and their culture supernatants, respectively, thereby investigating the anti-inflammatory effects of 4MC. Western blot was used to examine the expressions of nuclear factor κB (NF-κB) signaling pathway-related proteins, including inhibitor of NF-κB-α (IKBα), phosphorylated (P)-IκBα, NF-κB-inducing kinase α (IKKα), P-IKKαβ, P-p65, and p65. Cellular immunofluorescence was utilized to detect the expression and localization of p65 in RA-FLS, exploring whether 4MC exerts its anti-inflammatory effects by regulating the NF-κB signaling pathway. Finally, a collagen-induced arthritis (CIA) mouse model was established. The anti-RA effect of 4MC in vivo was evaluated by gross observation and histological examination. RESULTS: 4MC inhibited RA-FLS migration in a concentration-dependent manner. In the TNF-α-induced RA-FLS inflammation model, 4MC significantly decreased the gene and protein expression levels of IL-1β and IL-6. Furthermore, 4MC markedly reduced the ratios of P-IΚBα/IΚBα, P-IKKαβ/IKKα, and P-p65/p65, thereby blocking the transcriptional activity of p65 by inhibiting its nuclear translocation. This mechanism effectively suppressed the activation of the TNF-α-mediated NF-κB signaling pathway. Animal studies demonstrated that 4MC [10 mg/(kg·day)] significantly lowered serum levels of IL-1β, IL-6, and TNF-α, and alleviated arthritis severity and bone destruction in CIA mice. CONCLUSION 4MC not only inhibits the migration of RA-FLS but also mitigates their inflammatory response by suppressing the NF-κB signaling pathway, thereby effectively exerting its anti-RA effects.
Synoviocytes/metabolism* ; Arthritis, Rheumatoid/metabolism* ; Animals ; Cell Movement/drug effects* ; Humans ; Catechols/therapeutic use* ; Fibroblasts/drug effects* ; Mice ; Tumor Necrosis Factor-alpha/pharmacology* ; Interleukin-1beta/metabolism* ; Interleukin-6/metabolism* ; Signal Transduction/drug effects* ; NF-kappa B/metabolism* ; Transcription Factor RelA/metabolism* ; Synovial Membrane/cytology* ; Cells, Cultured ; Male ; Arthritis, Experimental ; Anti-Inflammatory Agents/pharmacology* ; NF-KappaB Inhibitor alpha ; Inflammation

Objectives miR-207 has been identified as being expressed in natural killer (NK) cell exosomes that play a role in disease progression; however, to date, there are no studies specifically linking miR-207 to tuberculosis (TB). Methods Bioinformatics methods employed for prediction, followed by a dual luciferase reporter assay to determine whether lysosome-associated membrane protein 2 (LAMP2) is targeted by miR-207. The experiments were divided into four groups using the liposome transfection method (OP-LAMP2 group: co-transfected with miR-207 mimics and LAMP2 overexpression plasmid; EP group: co-transfected with mimics NC and null-loaded plasmid; siLAMP2 group: transfected with siLAMP2; and siLAMP2-NC group: transfected with siLAMP2-NC). TB infection was modeled using H37Ra-infected Ana-1 cells. The impact of LAMP2 on intracellular mycobacterial load and clearance of extracellular residual mycobacteria were assessed by tuberculosis colony-forming unit counting. Flow cytometry was used to assess the total apoptosis rate. Real-time fluorescent quantitative PCR was conducted to determine the relative expression of LAMP2, apoptosis genes, pyroptosis genes, and autophagy genes. Western blot analysis was performed to measure the relative expression of LAMP2 proteins, apoptosis proteins, pyroptosis proteins, and autophagy proteins. Results Dual luciferase reporter assay test showed that there was a targeting relationship between LAMP2 and miR-207. The transfection model was successfully constructed under real-time fluorescent quantitative PCR and Western blot statistical analysis, and microscopic observation. The infection model was successfully established under microscopic observation. Colony forming unit counting revealed that the number of colonies in the OP-LAMP2 group was lower than that in the EP group, while the number of colonies in the siLAMP2 group was higher than that in the siLAMP2-NC group. Flow cytometry assay revealed that the total apoptosis in OP-LAMP2 group was lower than that in EP group, and the total apoptosis in siLAMP2 group was higher than that in siLAMP2-NC group. Real-time fluorescence quantitative PCR and Western blot analysis revealed that the relative expression of apoptosis and pyroptosis-related proteins and genes in the control group was lower in the OP-LAMP2 group compared to the EP group, and higher in the siLAMP2 group compared to the siLAMP2-NC group. Real-time fluorescence quantitative PCR detected that the relative expression of autophagy positively regulated genes Microtubule-associated protein 1 light chain 3(LC3)and Beclin1 in the OP-LAMP2 group was higher in the OP-LAMP2 group compared to the EP group, and lower in the siLAMP2 group compared to the siLAMP2-NC group, while the relative expression of negatively regulated autophagy genes followed the opposite trend to that of autophagy positively regulated genes. The relative expression of autophagy-related proteins was consistent with the trend of autophagy genes. Conclusions miR-207 enhances macrophage apoptosis, cellular pyroptosis and inhibits autophagy, promoting survival of Mycobacterium tuberculosis by targeting the autophagy-related protein LAMP2, thus offering a novel therapeutic direction for tuberculosis.
Lysosomal-Associated Membrane Protein 2/metabolism* ; MicroRNAs/metabolism* ; Mycobacterium tuberculosis/physiology* ; Autophagy/genetics* ; Humans ; Macrophages/metabolism* ; Apoptosis/genetics* ; Tuberculosis/metabolism* ; Cell Line ; Pyroptosis/genetics*

Objective To investigate the effects of hyaluronic acid and proteoglycan-linked protein 1 (HAPLN1) secreted by synovial fibroblasts (FLS) on the polarization of macrophages (Mϕ) in rheumatoid arthritis (RA). Methods Human monocytic leukemia cells (THP-1) were differentiated into Mϕ, which were subsequently exposed to recombinant HAPLN1 (rHAPLN1). RA-FLS were transfected separately with HAPLN1 overexpression plasmid (HAPLN1^OE) or small interfering RNA targeting HAPLN1 (si-HAPLN1), and then co-cultured with Mϕ to establish a co-culture model. The viability of Mϕ was assessed using the CCK-8 assay, and the proportions of pro-inflammatory M1-type and anti-inflammatory M2-type Mϕ were analyzed by flow cytometry. Additionally, the expression levels of inflammatory markers, including interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), and inducible nitric oxide synthase (iNOS), were quantified using quantitative real-time PCR and Western blot analysis. Results The viability of Mϕ was increased in the rHAPLN1 group compared to the control group. Furthermore, both the M1/Mϕ ratio and inflammatory factor levels were elevated in the rHAPLN1 and HAPLN1^OE groups. In contrast, the si-HAPLN1 group exhibited a decrease in the M1/Mϕ ratio and inflammatory factor expression. Notably, the introduction of rHAPLN1 in rescue experiments further promoted Mϕ polarization towards the M1 phenotype. Conclusion HAPLN1, secreted by RA fibroblast-like synoviocytes (RA-FLS), enhances Mϕ polarization towards the M1 phenotype.
Humans ; Arthritis, Rheumatoid/genetics* ; Macrophages/immunology* ; Fibroblasts/metabolism* ; Phenotype ; Extracellular Matrix Proteins/genetics* ; Proteoglycans/genetics* ; Synovial Membrane/cytology* ; Tumor Necrosis Factor-alpha/genetics* ; Interleukin-1beta/genetics* ; Nitric Oxide Synthase Type II/genetics* ; Cell Differentiation ; Coculture Techniques ; THP-1 Cells

Objective To investigate the effect of FUNDC1 tyrosine phosphorylation site mutations on mitophagy in H9c2 myocardial cells by constructing tyrosine site mutant plasmids (Y11 and Y18) of the FUN14 domain-containing protein 1 (FUNDC1). Methods The mutant plasmids constructed by whole-gene synthesis were transfected into rat myocardial H9c2 cells and divided into five groups: empty plasmid group, FUNDC1 overexpression group, Y11 mutant group, Y18 mutant group, and Y11 combined with Y18 mutant group. The viability of H9c2 cells was assessed using the CCK-8 assay. Additionally, tetramethylrhodamine ethyl ester (TMRE) staining was utilized to detect mitochondrial membrane potential. The protein expression levels of FUNDC1, translocase of the outer mitochondrial membrane 20 (TOM20), and cytochrome c oxidase IV (COX IV) were detected by Western blot analysis. Confocal microscopy was used to evaluate transfection efficiency as well as the co-localization of mitochondria and lysosomes. Results The FUNDC1 overexpression, Y11, Y18, and Y11 combined with Y18 mutant plasmids were successfully constructed. After plasmid transfection, widespread GFP fluorescence expression was observed under confocal microscopy. Compared with the empty plasmid group, FUNDC1 protein expression levels were significantly increased in the FUNDC1 overexpression group, Y11 mutation group, Y18 mutation group, and Y11 combined with Y18 mutation group, while cell viability and mitochondrial membrane potential showed no significant changes. Compared to the empty plasmid group, cells transfected with Y18 and Y11 combined with Y18 mutant plasmids showed increased TOM20 and COX IV expression levels and decreased mitochondrial-lysosomal co-localization. Conclusion Transfection with FUNDC1 Y18 or Y11 combined with Y18 mutant plasmids inhibited mitophagy in H9c2 myocardial cells.
Animals ; Rats ; Mitophagy/genetics* ; Myocytes, Cardiac/cytology* ; Mitochondrial Proteins/metabolism* ; Mutation ; Phosphorylation ; Tyrosine/genetics* ; Cell Line ; Membrane Proteins/metabolism* ; Membrane Potential, Mitochondrial