Astragaloside IV attenuates apoptosis of H9c2 cardiomyocytes induced by angiotensin II

AIM: To investigate the protective effect of astragaloside IV (ASIV) on angiotensin II (Ang II)- induced apoptosis of H9c2 cardiomyocytes. METHODS: H9c2 cardiomyocytes were treated with different concentrations of Ang II and ASIV. The effects of Ang II and ASIV on the viability of H9c2 cells was measured by CCK-8 assay. The optimum concentration of Ang II was 1 μmol/L and the concentrations of ASIV were 25, 50 and 100 μmol/L. The H9c2 cells was divided into 6 groups:control group, ASIV group, Ang II group, Ang II+ASIV (25 μmol/L) group, Ang II+ASIV 50 (μmol/L) group and Ang II+ASIV (100 μmol/L) group. The morphological changes of the H9c2 cells were observed under inverted phase-contrast microscope. Apoptosis was detected by TUNEL assay. The generation of reactive oxygen species (ROS) was detected by DCFH-DA staining. The protein expression of Bax, Bcl-2, nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) was determined by Western blot. H9c2 cardiomyocytes were transfected with negative control shRNA (NC) or Nrf2-shRNA (shRNA), and the cells were divided into 8 groups:NC+control group, NC+AngⅡgroup, NC+ASIV group, NC+AngⅡ+ASIV group, shRNA+control group, shRNA+AngⅡgroup, shRNA+ASIV group and shRNA+AngⅡ+ASIV group. ROS level was detected by ROS detection kit. The protein expression of Nrf2 and HO-1 was determined by Western blot. RESULTS: Ang II decreased the viability of H9c2 cells in a concentration-dependent manner (P<0.05). ASIV reversed the effect of Ang II on the viability of H9c2 cells in a concentration-dependent manner (P<0.05). Compared with control group, the apoptotic rate, the level of ROS and the protein expression of Bax in Ang II group were increased significantly, while the protein expression of Bcl-2, Nrf2 and HO-1 was decreased significantly (P<0.05). Compared with Ang II group, ASIV reversed the increase in apoptotic rate of H9c2 cells induced by Ang II in a concentration-dependent manner, reduced ROS level, down-regulated the protein expression of Bax and up-regulated the protein expression of Bcl-2, Nrf2 and HO-1 (P<0.05). After shRNA transfection, the effects of ASIV decreasing ROS production induced by Ang II and up-regulating the expression of Nrf2 and HO-1 were eliminated. CONCLUSION: ASIV protects H9c2 cardiomyocytes from apoptosis induced by Ang II, which may be related to reducing ROS generation and mediating the Nrf2/HO-1 signaling pathway.     

Opening of ATP-sensitive K+ channels protects H9c2 cardiac cells against high glucose-induced injury and inflammation by inhibiting TLR4/NF-κB pathway

AIM: To investigate whether the opening of ATP-sensitive K⁺(K_ATP) channels protects H9c2 cardiac cells against high glucose(HG)-induced injury and inflammation by inhibiting the Toll-like receptor 4(TLR4)/nuclear factor-κB(NF-κB) pathway. METHODS: The protein levels of TLR4 and NF-κB p65 were determined by Western blot. The levels of interleukin-1β(IL-1β) and tumor necrosis factor-α(TNF-α) were detected by ELISA. The cell viability was measured by CCK-8 assay. Mitochondrial membrane potential(MMP) was examined by rhodamine 123(Rh 123) staining followed by photofluorography. The intracellular levels of reactive oxygen species(ROS) were detected by 2', 7'-dichlorfluorescein- diacetate(DCFH-DA) staining followed by photofluorography. The number of apoptotic cells was observed by Hoechst 33258 nuclear staining followed by photofluorography. RESULTS: After the H9c2 cardiac cells were treated with HG(35 mmol/L glucose) for 24 h, the protein levels of TLR4 and phosphorylated NF-κB p65(p-NF-κB p65) were significantly increased. Pretreatment of the cells with 100 μmol/L diazoxide(DZ, a K_ATP channel opener) for 30 min before exposure to HG considerably blocked the up-regulation of the TLR4 and p-NF-κB protein levels induced by HG. Moreover, co-treatment of the cells with 30 μmol/L TAK-242(an inhibitor of TLR4) obviously inhibited the HG-induced up-regulation of the p-NF-κB p65 protein level. On the other hand, pretreatment of the cells with 100 μmol/L DZ had a clear myocardial protection effect, which attenuated the HG-induced cytotoxicity, inflammatory response, mitochondrial damage, oxidative stress and apoptosis, evidenced by an increase in the cell viability, and decreases in the levels of IL-1β and TNF-α, MMP loss, ROS generation and the number of apoptotic cells. Similarly, co-treatment of H9c2 cardiac cells with 30 μmol/L TAK-242 or 100 μmol/L PDTC(an inhibitor of NF-κB) and HG for 24 h also obviously reduced the above injuries and inflammation induced by HG.CONCLUSION: The opening of K_ATP channels protects H9c2 cardiac cells against HG-induced injury and inflammation by inhibiting the TLR4/NF-κB pathway.     

矮化中间砧‘宫藤富士’苹果栽植密度对树体生长、冠层光照和果实产量的影响

以2011年春季定植的矮化中间砧苹果成品苗(3年根1年干的‘宫藤富士’/SH6/平邑甜茶)为试材,设置7种不同的栽植密度(株行距分别为1 m×3 m、1.5 m×3 m、2 m×3 m、0.75 m×4 m、1 m×4 m、1.25 m×4 m和1.5 m×4 m),细纺锤形整枝修剪,自栽植第2年,连续7年调查7种栽植密度对树体生长、冠层光照分布、果实产量和品质的影响。随着树龄的增长,不同栽植密度下树干粗度和总枝量逐年增加,不同处理间树干粗度无显著差异,第7年1 m×3 m和0.75 m×4 m两个栽植密度下树体总枝量超过140万条·hm-2,第8年均超过140万条·hm^-2。栽植前期(第2～4年)各栽植密度树体短枝比例不断增加,长枝比例不断减少,第5年各栽植密度枝类组成趋于稳定;综合稳产3年(第6～8年)树体的枝类组成数据,4 m行距的短枝比例明显高于3 m行距,长枝比例略低。树体冠层平均相对光照强度由高到低的株行距处理依次为1.5 m×4 m(63.87%)、1.25 m×4 m(61.44%)、2 m×3 m(61.27%)、1 m×4 m(59.19%)、...     

AT1-AA induces autophagy and apoptosis of H9c2 cardiomyocytes through oxidative stress

AIM: To investigate the effects of angiotensin Ⅱ type 1 receptor autoantibody (AT1-AA) on oxidative stress, autophagy and apoptosis in H9c2 cells, and to analyze the possible mechanism. METHODS: The rat H9c2 cells were cultured in vitro. The effect of AT1-AA at different concentrations for different time on the cell viability was measured by CCK-8 assay. Upon the optimum concentration (10^-5 mol/L) and time point (24 h) determined in this stu-dy, the experssion levels of autophagy- and apoptosis-related proteins were detected by Western blot, and the levels of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and malondialdehyde (MDA) were examined by oxidative stress kits. RESULTS: AT1-AA decreased cell viability in a concentration- and time-dependent manner, promoted apoptosis, and up-regulated the levels of autophagy and oxidative stress (P<0.05). The apoptosis of H9c2 cells induced by AT1-AA was decreased after pretreatment with autophagy inhibitor 3-methyladenine (P<0.05). The levels of autophagy and apoptosis in the H9c2 cells pretreated with α-lipoic acid were decreased (P<0.05). Pretreatment with angiotensin Ⅱtype 1 receptor inhibitor telmisartan inhibited oxidative stress, and significantly decreased the levels of autophagy and apoptosis induced by AT1-AA in the H9c2 cells (P<0.05). CONCLUSION: AT1-AA induces autophagy and apoptosis of H9c2 cells through oxidative stress.     

Inhibitory effect of acetylcholine on apoptosis of myocardial H9c2 cells induced by norepinephrine

AIM: To investigate the inhibitory effect of acetylcholine (ACh) on the apoptosis of myocardial H9c2 cells induced by norepinephrine (NE). METHODS: The apoptosis model of myocardial H9c2 cells was established by treating the cells with NE at different concentrations, and ACh was used to observed the protective effect. The cell viability was measured by MTT assay and the optimal doses of NE and ACh were selected. Four blockers related to different signaling pathways were also used. The apoptotic rate was analyzed by flow cytometry with Annexin V-FITC/PI staining. JC-1 staining was used to observe the changes of mitochondrial membrane potential of the H9c2 cells. DCFH-DA staining was used to observe intracellular reactive oxygen species (ROS) production. RESULTS: The viability of H9c2 cells was decreased by treatment with NE at 10 μmol/L. The membrane potential of mitochondria was decreased, while ROS production and apoptotic rate were increased significantly (P<0.05). Pretreatment with ACh at 10 mmol/L resulted in the increase in cell viability and decrease in the ROS production, and inhibited the loss of mitochondrial membrane potential and cell apoptosis (P<0.05). After treatment with the 4 signaling pathway blockers before ACh, the protective effect of ACh was significantly reduced only by PDTC. CONCLUSION: ACh inhibits the apoptosis of H9c2 cells induced by NE, and its mechanism may be related to NF-κB signaling pathway.     

miR-323 regulates hypoxia-induced apoptosis of H9C2 cardiomyocytes through FGF9

AIM: To investigate the effect of microRNA-323 (miR-323) on the apoptosis of hypoxia-induced rat H9C2 cardiomyocytes and its mechanism. METHODS: The hypoxic injury model was established in the H9C2 cells. Anti-miR-323, pcDNA-FGF9 and si-FGF9 were transfected into the H9C2 cells and cultured under hypoxic condition for 48 h. The expression of miR-323 was detected by qPCR. The protein levels of fibroblast growth factor 9 (FGF9), cleaved caspase-3, c-Jun N-terminal kinase (JNK) and p-JNK were determined by Western blot. The cell viability was measured by MTT assay, and the apoptosis was analyzed by flow cytometry. The method of bioinformatics was applied to predict the target gene of miR-323, and dual-luciferase reporter assay was used for further validation. RESULTS: Hypoxia greatly reduced the viability of H9C2 cells at 12 h, 24 h and 48 h (P<0.05), and remarkably increased apoptotic rate and the protein level of cleaved caspase-3 in a time-dependent manner (P<0.05). The expression of miR-323 and the protein level of p-JNK were up-regulated and the expression of FGF9 was down-regulated in the H9C2 cells exposed to hypoxia (P<0.05). Down-regulation of miR-323 and over-expression of FGF9 obviously increased the viability of the H9C2 cells exposed to hypoxia, and decreased the apoptotic rate and the protein level of cleaved caspase-3 (P<0.05). FGF9 was the target gene of miR-323. Down-regulation of FGF9 reversed the attenuating effect of down-regulation of miR-323 on hypoxia-induced H9C2 cell injury. miR-323 regulated FGF9 and affected p-JNK level. CONCLUSION: miR-323 affects the viability and apoptosis of H9C2 cardiomyocytes under hypoxia by targeting FGF9 and regulating JNK signaling pathway.     

Protective effects and mechanisms of losartan on apoptosis of H9c2 cells induced by β-adrenergic stimulation in vitro

AIM: To investigate the protective effect of losartan (Los) on apoptosis of H9c2 cells induced by isoprenaline (ISO), and to discover its related mechanism. METHODS: H9c2 cells cultured on plastic plates were divided into control, ISO, ISO+Los, ISO+Los+LY294002 and DMSO groups. Cell apoptosis was evaluated by flow cytometery and agarose gel electrophoresis. The mRNA levels of bax, bcl-2 and caspase-9 were detected by RT-PCR and the expressions of phosphorylated and total Akt (p-Akt and t-Akt) were assessed by Western blotting. The cAMP was measured by radioimmunoassay. RESULTS: ISO at concentration of 10 μmol/L induced apoptosis of H9c2 with an increase in bax/bcl-2, caspase-9 and cAMP. Addition of 10 μmol/L losartan inhibited apoptosis obviously with a decrease in bax/bcl-2, caspase-9 and cAMP. A significant increase in p-Akt was observed, and its protein level was elevated. LY294002 at concentration of 1 μmol/L abolished the protective effects of losartan on ISO-induced apoptosis in H9c2 cells. CONCLUSION: ISO might induce H9c2 cell apoptosis through stimulation of β-adrenergic receptor (β-AR). Los inhibits downstream signaling of β-AR, and promotes the activation of Akt. Subsequently it might attenuate the apoptosis induced by β-adrenergic stimulation of ISO.     

Apelin-13 inhibits nicotine-induced apoptosis of H9c2 cells via PI3K/Akt signaling pathway

AIM:To investigate the effect of apelin-13 on nicotine-induced apoptosis of cardiomyocytes and its potential molecular mechanism. METHODS:Rat H9c2 cells were treated with nicotine (10 μmol/L) to induced apoptosis. Flow cytometry was used to detect apoptotic rate. Western blot was used to determined the expression of related proteins. RESULTS:Compared with control group, nicotine treatment significantly increased the apoptotic rate of the H9c2 cells (P<0.01), and the protein levels of apoptosis-related proteins Bax and cleaved caspase-3, but markedly decreased the protein levels of Bcl-2, p-Akt, p-PI3K and APJ (P<0.05). Compared with nicotine group, apelin-13+nicotine significantly decreased the apoptotic rate of the H9c2 cells (P<0.01) and the the protein levels of Bax and cleaved caspase-3, but markedly increased the protein levels of Bcl-2, p-Akt, p-PI3K and APJ (P<0.05). Compared with apelin-13+nicotine group, apelin-13+nicotine+PI3K/Akt inhibitor LY294002 significantly increased the apoptotic rate of the H9c2 cells (P<0.01) and the protein levels of Bax and cleaved caspase-3, but markedly decreased the protein levels of Bcl-2, p-Akt and p-PI3K (P<0.05). CONCLUSION:Apelin-13 inhibits nicotine-induced apoptosis of H9c2 cells through PI3K/Akt signaling pathway.     

Effect of adipose differentiation-related protein on proliferation and apoptosis in H9c2 cells

AIM: To construct an adipose differentiation-related protein (ADRP) eukaryotic expression vector and to explore the effect of ADRP on apoptosis of H9c2 cells induced by palmitic acid (PA). METHODS: The ADRP gene obtained by the method of RT-PCR was cloned into pEGFP-C1 plasmid. The recombinant plasmid was transformed into E.coli DH5α for amplification. The recombinant plasmid was extracted from E.coli DH5α and transfected into H9c2 cells by Lipofectamine^TM2000. The stable transformants were selected by G418 screening. Expression of green fluorescent protein was observed under fluorescence microscope and the ADRP expression was identified by RT-qPCR and Western blotting analysis. The effect of PA on the proliferation of H9c2 cells was detected by MTT assay. The apoptotic percentage of H9c2 cells caused by PA was determined by flow cytometry. RESULTS: The eukaryotic expression vector pEGFP-C1-ADRP was successfully constructed. Green fluorescent was observed in the cells transfected with pEGFP-C1 or pEGFP-C1-ADRP under fluorescence microscope. RT-qPCR and Western blotting analysis showed that recombinant cells exhibited high mRNA and protein levels of ADRP. After treated with PA at different concentrations, the apoptosis rates and the proliferation inhibition of recombinant cells were both lower than those of the other two cells. CONCLUSION: The transfected H9c2 cells with stable ADRP expression were successfully established. The over-expression of ADRP prevents the cells from apoptosis and inhibition of proliferation caused by PA, indicating that ADRP plays a protective role in H9c2 cells.     

Dengue virus type 2 induces apoptosis of RAW264.7 cells and effect of apoptosis on virus replication

AIM:To explore the apoptotic pathway in dengue virus type 2 (DENV2)-infected RAW264.7 cells and to analyze the effect of apoptosis on virus replication. METHODS:RAW264.7 cells were infected with DENV2. MTT assay was used to detect the cell viability. Apoptosis was assessed by Hoechst 33342 staining and Annexin V-FITC/PI staining. The expression levels of caspase-3 and caspase-8 were determined by Western blotting. The activity of caspase-9 was measured with a colorimetric kit. Mitochondrial membrane potential was evaluated using JC-1 fluorescent staining. TCID50 was used to estimate the infectious virion concentration after using Z-VAD-FMK to inhibit apoptosis. RESULTS:The viability of RAW264.7 cells decreased after DENV2 infection at 24 h, 36 h and 48 h. Karyopyknosis in dengue virus-infected cells was observed. The protein levels of caspase-3 and caspase-8 and the activity of caspase-9 increased in the apoptotic cells after dengue virus infection. Mitochondrial membrane potential was reduced after dengue virus infection. There was a higher virion concentration in the cell culture medium after inhibition of apoptosis. CONCLUSION: Dengue virus induces apoptosis of RAW264.7 cells. Apoptotic inhibition of RAW264.7 cells facilitates the production of dengue virus.     

CaMKII aggravates hypoxia/reoxygenation injury in H9c2 cells by activating apoptosis

AIM: To investigate the effect of Ca²⁺/calmodulin-dependent protein kinase Ⅱ (CaMKⅡ) on hypoxia/reoxygenation (H/R) injury in H9c2 cells. METHODS: H9c2 cells were randomized into 4 groups:control group, KN-93 (an inhibitor of CaMKⅡ; 1 μmol/L) treatment group, H/R group and H/R+KN-93 (1 μmol/L) treatment group. The cells in KN-93 group and KN-93+H/R group were pretreated with KN-93 for 2 h before the other treatment was performed. The viability of H9c2 cells in each group was measured by CCK-8 assay. Lactate dehydrogenase (LDH) activity in the culture medium was detected. The protein levels of phosphorylated CaMKⅡ (p-CaMKⅡ), phosphorylated phospholamban (p-PLN) and cleaved caspase-3 were determined by Western blot. The apoptosis was analyzed by TUNEL staining and the flow cytometry. RESULTS: No significant difference of all indexes tested between control group and KN-93 group was observed. H/R treatment significantly reduced the cell viability, and increased the activity of LDH (P<0.01), the protein levels of p-CaMKⅡ, p-PLN and cleaved caspase-3 (P<0.05), and the apoptotic rate (P<0.01). KN-93 (1 μmol/L) significantly increased the cell viability, and decreased the activity of LDH (P<0.01), the protein levels of p-CaMKⅡ, p-PLN and cleaved caspase-3 (P<0.05), and the apoptotic rate (P<0.01). CONCLUSION: CaMKⅡ aggravates hypoxia/reoxygenation injury in the H9c2 cells by activating apoptosis.     

Protective effect of ecdysterone on H9c2 cells against oxidative stress

AIM: To investigate the effect of ecdysterone (EDS) on H9c2 cardiomyocytes after oxidative stress. METHODS: H9c2 cells were cultured in vitro and divided into control group, high dose (2 μmol/L) of EDS group, middle dose (1.5 μmol/L) of EDS group, low dose (1 μmol/L) of EDS group, and H₂O₂ group. H9c2 cardiomyocytes in H₂O₂ group and high, middle and low doses of EDS groups were exposed to H₂O₂ for 6 h to establish the model of oxidative stress. The viability of the H9c2 cells was detected by CCK-8 assay. The apoptosis of H9c2 cells was analyzed by flow cytometry. The levels of lactate dehydogenase (LDH) and creatine kinase-MB (CK-MB) in the culture medium, and the levels of superoxide dismutase (SOD) and malondialdehyde (MDA) in the H9c2 cells were measured by colorimetry. The generation of reactive oxygen species (ROS) and the mitochondrial membrane potential were evaluated by flow cytometry and confocal laser scanning microscopy. The protein levels of Bax, Bcl-2 and cleaved caspase-3 in the H9c2 cells were determined by Western blot. RESULTS: Ecdysterone at the selected concentrations had no effect on the viability of H9c2 cells. Compared with control group, the levels of LDH, CK-MB, ROS and MDA, and the apoptotic rates of the H9c2 cells were significantly increased after treated with H₂O₂, but were decreased by EDS treatment in a dose-dependent manner. The levels of SOD and mitochondrial membrane potential of the H9c2 cells in H₂O₂ group were reduced significantly compared with control group, but high, middle and low doses of EDS treatments up-regulated the levels of SOD and mitochondrial membrane potential in H₂O₂-treated H9c2 cells. The protein levels of Bax and cleaved caspase-3 in the H9c2 cells in H₂O₂ group showed significant elevation in comparison with control group, and the protein expression of Bcl-2 declined in H₂O₂ group compared with control group, but high, middle and low doses of ecdysterone treatments down-regulated the protein levels of Bax, cleaved caspase-3 and up-regulated the expression of Bcl-2 in H₂O₂-treated H9c2 cells. CONCLUSION: Ecdysterone attenuates the effect of H₂O₂-induced oxidative stress on H9c2 cardiomyocytes. The mechanism may be involved in scavenging oxidative stress products, increasing antioxidant enzyme activity and improving mitochondrial function.     

Effects of rAAV9-mediated siRNA for p65 knockdown on myocardial fibrosis and apoptosis in rats with pressure overload

AIM To investigate the effect of p65 gene knock-down mediated by recombinant adeno-associated virus serotype 9 （rAAV9） on the cardiac function of pressure overload rat and its possible mechanism. METHODS The rat model of left ventricular hypertrophy was established by abdominal aortic coarctation（AAC）. SD rats were randomly divided into sham operation group, AAC group, AAC+rAAV9-eGFP group and AAC+rAAV9-eGFP-P65-siRNA group. The abdominal cavity was closed directly after laparotomy in the rats of sham operation group, the abdominal cavity was closed after ligation of the abdominal aorta in the rats of AAC group, and normal saline, rAAV9-eGFP and rAAV9-eGFP-P65-siRNA were injected into the tail vein 3 d after operation. After 4 weeks, the hemodynamic indexes were measured, the heart mass parameters were calculated, the degree of myocardial fibrosis was detected by Masson staining, the expression level of myocardial P65 was detected by Western blot, the degree of apoptosis was detected by TUNEL staining, and the serum contents of tumor necrosis factor-α （TNF-α） and interleukin-6 （IL-6） of the rats in each group were measured by ELISA. RESULTS The expression of P65 in AAC group and AAC+rAAV9-eGFP group was higher than that in sham operation group, while the expression of P65 in AAC+rAAV9-eGFP-P65-siRNA group was significantly lower than that in AAC group. The levels of systolic blood prossure （SBP）, diastolic blood pressure （DBP）, left ventricular weight/body weight （LVW/BW）, cardiomyocyte apoptotic rate and TNF- α and IL-6 in AAC group and AAC+rAAV9-eGFP group were higher than those in sham operation group, while SBP, DBP, LVW/BW, cardiomyocyte apoptosis rate and TNF-α in AAC+rAAV9-eGFP-P65-siRNA group were significantly lower than those in AAC group. The results of Masson staining showed that the deposition of collagen in cardiac tissue in AAC group and AAC+rAAV9-eGFP group was higher than that in sham operation group, and treatment with rAAV9-eGFP-P65-siRNA alleviated hypertension-induced fibrosis. CONCLUSION Knockdown of p65 gene reduces the degree of left ventricular fibrosis and apoptosis in rats with stress overload, and its mechanism is related to the regulation of NF-κB pathway and the reduction of inflammatory response.     

Critical role of cystic fibrosis transmembrane conductance regulator in hypoxia-induced apoptosis of H9c2 cardiomyocytes

AIM:To explore the roles of cystic fibrosis transmembrane conductance regulator (CFTR) in hypoxia-induced apoptosis of H9c2 cardiomyocytes and the underlying mechanisms. METHODS:The rat H9c2 cardiomyocytes were exposed to a 1% hypoxic environment in a hypoxic chamber. After CFTR overexpression, H9c2 cardiomyocytes were cultured in a hypoxic environment. The mRNA and protein levels of CFTR were examined by RT-qPCR and Western blot, respectively. The cell viability was measured by MTT assay. The apoptotic rate was determined by Hoechst 33342 and Annexin V-FITC/PI staining, and the production of reactive oxygen species (ROS) was examined by dichloro-dihydro-fluorescein diacetate (DCF-DA) staining. RESULTS:Hypoxic exposure caused the apoptosis of H9c2 cardiomyocytes, which was accompanied by the down-regulation of CFTR at mRNA and protein levels and over-production of ROS (P<0.05). After CFTR overexpression, the apoptotic rate of the H9c2 cardiomyocytes induced by hypoxia was significantly reduced, with a prominent inhibition of ROS production (P<0.05). However, pretreatment with CFTRinh-172, a specific inhibitor of CFTR, reversed the protective effect of CFTR overexpression in H9c2 cardiomyocytes. CONCLUSION:CFTR has a critical role in protecting against hypoxia-induced apoptosis of H9c2 cells, which may be through inhibiting the generation of ROS.     

Effect of AMD3100 on dengue virus type 2-induced apoptosis in Eahy926 cells

AIM: To investigate the role of AMD3100 (an inhibitor of CXCR4) in dengue virus type 2 (DV2)-induced apoptosis in human umbilical vein endothelial cell line Eahy926. METHODS: The expression of factor Ⅷ in Eahy926 cells was examined by immunohistochemistry staining. The cells were divided into untreated group, DV2 infection group and DV2+AMD3100 group. Flow cytometric analysis was used to detect the expression of CXCR4 in Eahy926 cells 24 h, 36 h, 48 h and 60 h after DV2 infection. In addition, the percentage of apoptotic cells was also analyzed by flow cytometry. Immunofluorescence was performed to detect the phosphatidylserine (PS) on the surface of Eahy926 cells.RESULTS: Eahy926 cells were factor Ⅷ-positive. Compared with untreated group, the expression of CXCR4 increased in DV2 infection group, most markedly 48 h after infection (66.13%±10.30%, P<0.05). The percentage of apoptotic Eahy926 cells after DV2 infection was the highest at 36 h (29.85%±15.78%, P<0.05). The percentage of DV2-induced apoptotic cells in DV2+AMD3100 group was higher than that in DV2 infection group. The green fluorescence-labeled cells in DV2 infection group and DV2+AMD3100 group were more than those in untreated group. CONCLUSION: DV2 infection induces apoptosis and increases the expression of CXCR4 in Eahy926 cells. AMD3100, the inhibitor of CXCR4, may be a promoter of apoptosis in Eahy926 cells after DV2 infection.     

Effect of miR-25 on apoptosis of H9c2 cells induced by hypoxia/reoxygenation

AIM:To investigate the role and mechanism of microRNA-25 (miR-25) in apoptosis of H9c2 cells induced by hypoxia/reoxygenation. METHODS:The H9c2 cells with over-expression of miR-25 were treated with hypo-xia/reoxygenation. Real-time PCR was used to detect the expression of miR-25 and high mobility group box-1 (HMGB1) mRNA. Western blot was performed to examine the protein expression levels of HMGB1, Bcl-2 and cleaved caspase-3. Flow cytometry was used to analyze the proportion of apoptotic cells and the cell cycle. Dual-luciferase reporter assay was used to confirm that HMGB1 was the target gene of miR-25 in the H9c2 cells. Moreover, the H9c2 cells transfected with HMGB1-shRNA were subjected to hypoxia/reoxygenation to verify whether HMGB1 participated in the regulation of apoptosis of H9c2 cells. RESULTS:Over-expression of miR-25 significantly reduced the protein expression levels of HMGB1 and cleaved caspase-3, and increased the expression of Bcl-2 and the entrance into S phase in H9c2 cells induced by hypoxia/reoxygenation (P<0.01). The result of dual-luciferase reporter assay showed that compared with the control group, transfection with HMGB1-3' UTR-psi-CHECK2+miR-25 mimic strongly inhibited the luciferase activity (P<0.05). After the H9c2 cells transfected with HMGB1-shRNA was treated with hypoxia/reoxygenation, the expression of Bcl-2 was up-regulated, the expression of cleaved caspase-3 was down-regulated, and the cells in S phase were increased (P<0.05). CONCLUSION:miR-25 reduces apoptosis of H9c2 cells induced by hypoxia/reoxygenation, and its mechanism may be related with the inhibition of HMGB1 expression via interacting with its 3'-UTR.     

Hesperetin attenuates hypoxia/reoxygenation-induced apoptosis in H9c2 cells via inhibition of calcium overload

AIM: To investigate the effect of hesperetin on hypoxia/reoxygenation (H/R)-induced apoptosis in the H9c2 cells and to clarify the underlying mechanism. METHODS: The H/R model was established and the H9c2 cells were pretreated with hesperetin for 4 h. The cell viability and cell damage were measured by CCK-8 assay and lactate dehydrogenase (LDH) detection. The apoptosis was analyzed by Hoechst 33258 staining and flow cytometry. The intracellular calcium fluorescence intensity was measured by fluorescence microscopy and flow cytometry. The calcium-ATPase activity and the level of adenosine triphosphate (ATP) were measured by ELISA. The mitochondrial membrane potential was measured by JC-1 staining. The protein expression levels of Bcl-2, Bax and cytochrome C (Cyt-C) were determined by Western blot. RESULTS: Hesperetin reduced the apoptosis of the H9c2 cells induced by H/R, decreased intracellular Ca²⁺ fluorescence intensity, elevated Ca²⁺-ATPase activity, inhibited the mitochondrial membrane potential depolarization and increased the level of ATP (P<0.05). In addition, hesperetin significantly reduced the release of Cyt-C protein from mitochondria to cytoplasma and increased the Bcl-2/Bax ratio (P<0.05). After using the calcium ion inhibitor nimodipine, the percentage of the cells with mitochondrial membrane depolarization was decreased, the ATP level was increased and the protein expression of mitochondrion-related apoptosis molecules were decreased (P<0.05). CONCLUSION: Hesperetin reduces the apoptosis of the H9c2 cells induced by H/R, which may be related to inhibition of calcium overload and improvement of mitochondrial function.     

Effects of PTEN on apoptosis,oxidative damage and immune inflammatory factors in myocardial H9c2 cells with anoxia/reoxygenation

AIM: To investigate the effects of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) on the apoptosis, oxidative damage and immune inflammatory factors in myocardial H9c2 cells with anoxia/reoxygenation (A/R). METHODS: The H9c2 cells were used to establish a model of A/R. The H9c2 cells were transfected with PTEN small interfering RNA (siRNA) and negative control. After A/R, the expression of PTEN at mRNA and protein levels was determined by RT-PCR and Western blot, respectively. The cell viability was measured by MTT assay. The apoptosis was analyzed by flow cytometry. Xanthine oxidase method was used to determine superoxide dismutase (SOD) activity. The content of malondialdehyde (MDA) was detected by thiobarbituric acid method. The lactate dehydrogenase (LDH) activity in the supernatant was evaluated by 4-dinitrophenylhydrazine method. The levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6 in culture supernatant were examined by ELISA. The protein levels of cleaved caspase-3, Bax and FasL in the cells were determined by Western blot. RESULTS: After A/R, the expression of PTEN at mRNA and protein levels was significantly increased in the H9c2 cells (P<0.05). The mRNA and protein levels of PTEN were decreased significantly after transfection with PTEN siRNA (P<0.05). The viability of H9c2 cells was decreased after A/R, while the apoptotic rate was increased. The protein levels of cleaved caspase-3, Bax and FasL were increased in the cells. The MDA level was elevated, the activity of SOD was decreased, and the levels of LDH, TNF-α, IL-1β and IL-6 in the culture supernatant were increased (P<0.05). Down-regulation of PTEN partly antagonized the effects of A/R on the viability, apoptotic rate, MDA content, SOD activity, and the levels of LDH, TNF-α, IL-1β and IL-6 in culture supernatant. CONCLUSION: Down-regulation of PTEN attenuates oxidative damage induced by A/R, reduces apoptosis and secretion levels of TNF-α, IL-1β and IL-6 in the H9c2 cells.     

Expression and role of TRPM2 in H9N2 swine influenza virus infection-induced mouse pulmonary microvascular endothelial cell damage

AIM: To investigate the expression and role of transient receptor potential cation channel M2 (TRPM2) in H9N2 swine influenza virus (H9N2-SIV) infection-induced mouse pulmonary microvascular endothelial cell (PMEVC) damage. METHODS: At 24 h and 48 h after PMEVC (3 parallel test in each group) was infected by H9N2-SIV, the superoxide dismutase (SOD) activity, glutathione peroxidase (GSH-Px) activity, reactive oxygen species (ROS) level and nitric oxide synthase (NOS) activity were measured according to the manufacturer's instructions. The ultrastructural changes of PMVEC were observed under electron microscope. Transendothelial electrical resistance (TEER) and the percentage of horse radish peroxidase (HRP) influx was measure by Transwell culture. The expression of TRPM2 at mRNA and protein levels was determined by real-time PCR and Western blot. The apoptosis of PMVEC was observed with Annexin V/PI staining. RESULTS: The SOD and GSH levels were decreased significantly in H9N2-SIV-infected PMEVC as compared with control group(P<0.05). However, NOS activity and ROS level were increased dramatically (P<0.01). The organelles of PMVEC infected by H9N2-SIV were decreased sharply, and vacuolization in mitochondria and apoptosis were also observed under electron microscope. The value of TEER was decreased significantly and the percentage of HRP influx was increased dramatically with the H9N2-SIV infection (P<0.01). The expression of TRPM2 at mRNA and protein levels in H9N2-SIV-infected PMVEC was increased dramatically at 24 h and 48 h as compared with control group (P<0.01). Annexin V/PI double staining showed that the cytomembrane was stained by great green fluorescence and some nuclei were stained by red fluorescence in H9N2-SIV-infected PMVEC. However, less fluorescence stained PMVEC were found in control group. CONCLUSION: The expression of TRPM2 at mRNA and protein levels is increased significantly, which is involved in cell damage and apoptosis induced by oxidative stress of H9N2-SIV infection.