Mogroside regulates the oxidative stress response of retinal pigment epithelial cells induced by H 2O 2 through silent information regulator of transcription 1/nuclear factor erythroid-2-related actor 2 signaling pathway / 中华眼底病杂志

Objective:To observe and preliminarily explore the effect of mogroside on oxidative stress of retinal pigment epitheliaum (RPE) cells induced by hydrogen peroxide (H 2O 2) and its possible mechanism. Methods:A experimental study. The RPE cells were divided into control group, H 2O 2 group, silent information regulator of transcription 1 (SIRT1) inhibitor EX527 group (EX527 group), mogroside group, mogroside+EX527 group. Methyl thiazolete trazolium method was used to detect cell survival rate. Flow cytometry was used to detect cell apoptosis rate. 2' ,7'-dichlorodihydrofluorescein diacetate fluorescent probe method, xanthine method and enzyme-linked immunosorbent assay method were used to detect the level of reactive oxygen species (ROS), superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in cells respectively. Real-time quantitative polymerase chain reaction and Western blot were used to detect relative expressions of SIRT1, nuclear factor erythroid-2-related actor 2 (Nrf2), heme oxygenase-1 (HO-1) mRNA and protein in cells. One-way ANOVA was used for comparison among groups. The pairwise comparison between groups was tested by the least significant difference t test. Results:Compared with the control group, the H 2O 2 group cell survival rate decreased, the apoptosis rate increased, the ROS level in the cells increased, the SOD activity decreased, the MDA content increased, and the relative expression of SIRT1, Nrf2, HO-1 mRNA and protein decreased ( P<0.05). Compared with H 2O 2 group, the cell survival rate decreased, apoptosis rate increased, the cell ROS level increased, SOD activity decreased, MDA content increased, SIRT1, Nrf2, HO-1 mRNA and protein expression decreased in EX527 group ( P<0.05); the cell survival rate increased, apoptosis rate decreased, ROS level decreased, SOD activity increased, MDA content decreased, and the relative expression of SIRT1, Nrf2, HO-1 mRNA and protein increased in mogroside group ( P<0.05). Compared with the mogrosides group, the cell survival rate decreased, the apoptosis rate increased, the level of ROS increased, SOD activity decreased, MDA content increased, SIRT1, Nrf2, HO-1 mRNA and protein decreased in mogrosides+EX527 group ( P<0.05). Conclusions:Mogrosides can alleviate the oxidative stress response of visual RPE cells induced by H 2O 2, promote cell proliferation, and reduce cell apoptosis. Mogrosides may exert antioxidant effects by activating the SIRT1/Nrf2 signaling pathway.

Urolithin a alleviates oxidative stress-induced senescence in nucleus pulposus-derived mesenchymal stem cells through SIRT1/PGC-1α pathway.

BACKGROUND: In degenerative intervertebral disc (IVD), an unfavorable IVD environment leads to increased senescence of nucleus pulposus (NP)-derived mesenchymal stem cells (NPMSCs) and the inability to complete the differentiation from NPMSCs to NP cells, leading to further aggravation of IVD degeneration (IDD). Urolithin A (UA) has been proven to have obvious effects in delaying cell senescence and resisting oxidative stress. AIM: To explore whether UA can alleviate NPMSCs senescence and to elucidate the underlying mechanism. METHODS: In vitro, we harvested NPMSCs from rat tails, and divided NPMSCs into four groups: the control group, H2O2 group, H2O2 + UA group, and H2O2 + UA + SR-18292 group. Senescence-associated ß-Galactosidase (SA-ß-Gal) activity, cell cycle, cell proliferation ability, and the expression of senescence-related and silent information regulator of transcription 1/PPAR gamma coactivator-1α (SIRT1/ PGC-1α) pathway-related proteins and mRNA were used to evaluate the protective effects of UA. In vivo, an animal model of IDD was constructed, and X-rays, magnetic resonance imaging, and histological analysis were used to assess whether UA could alleviate IDD in vivo. RESULTS: We found that H2O2 can cause NPMSCs senescence changes, such as cell cycle arrest, reduced cell proliferation ability, increased SA-ß-Gal activity, and increased expression of senescence-related proteins and mRNA. After UA pretreatment, the abovementioned senescence indicators were significantly alleviated. To further demonstrate the mechanism of UA, we evaluated the mitochondrial membrane potential and the SIRT1/PGC-1α pathway that regulates mitochondrial function. UA protected mitochondrial function and delayed NPMSCs senescence by activating the SIRT1/PGC-1α pathway. In vivo, we found that UA treatment alleviated an animal model of IDD by assessing the disc height index, Pfirrmann grade and the histological score. CONCLUSION: In summary, UA could activate the SIRT1/PGC-1α signaling pathway to protect mitochondrial function and alleviate cell senescence and IDD in vivo and vitro.

Effects of HT-2 toxin on expressions of SIRT1, autophagy and apoptosis pathway related proteins in chondrocytes / 中华地方病学杂志

Objective:To explore the effects of HT-2 toxin on expressions of silent information regulator of transcription 1 (SIRT1) and autophagy and apoptosis pathway related proteins in cultured chondrocytes in vitro. Methods:The third-generation chondrocytes of SD neonatal rats aged 1 to 2 days were cultured in vitro and identified by toluidine blue staining and type Ⅱ collagen immunofluorescence staining. CCK-8 method was used to detect the proliferation of chondrocytes. According to the cell survival rate, 2, 4 and 8 ng/ml HT-2 toxin were selected for subsequent experiments, and the exposure time was 48 h. At the same time, a negative control group and a solvent (absolute ethanol) control group were set up. Western blotting was used to detect the expressions of SIRT1 and autophagy and apoptosis pathway related proteins [microtubule-associated protein 1 light chain 3 (LC3)-Ⅱ, LC3-Ⅰ, p62, Beclin1, Caspase-3, B-cell lymphoma-2 (Bcl-2) and Bcl-2-Associated X protein (Bax)] in each group. Results:After staining, the cells were identified as chondrocytes with high purity. The expression levels of SIRT1 protein in 2, 4, 8 ng/ml HT-2 toxin groups (0.69 ± 0.18, 0.46 ± 0.13, 0.35 ± 0.19) were significantly lower than that in negative control group (1.00 ± 0.39, P < 0.05). In 2, 4 and 8 ng/ml HT-2 toxin groups, the ratios of autophagy pathway related proteins LC3-Ⅱ and LC3-Ⅰ expressions (LC3-Ⅱ/LC3-Ⅰ, 1.47 ± 0.15, 1.37 ± 0.13, 1.81 ± 0.34) were higher than that in negative control group (1.00 ± 0.21, P < 0.05), and the expression levels of p62 protein in 4, 8 ng/ml HT-2 toxin groups (0.70 ± 0.04, 0.57 ± 0.01) were lower than that in negative control group (1.00 ± 0.15, P < 0.05). In 2, 4, 8 ng/ml HT-2 toxin groups, the expression levels of apoptosis pathway related protein Bcl-2 (0.61 ± 0.06, 0.54 ± 0.16, 0.47 ± 0.06) were significantly lower than that in negative control group (1.00 ± 0.14, P < 0.05), and the ratio of Bax to Bcl-2 protein expressions in 8 ng/ml HT-2 toxin group (Bax/Bcl-2, 3.27 ± 0.18) was higher than that in negative control group (1.00 ± 0.27, P < 0.05). The expression level of SIRT1 protein was significantly negatively correlated with the expression level of autophagy pathway related protein LC3-Ⅱ ( r = - 0.819, P < 0.01), and was significantly positively correlated with the expression level of p62 protein( r = 0.772, P < 0.01), but not with the expression level of Beclin1 protein ( r = 0.399 , P > 0.05); there was no correlation between SIRT1 protein expression and apoptosis pathway related protein Caspase-3 and Bax expressions ( r = - 0.297、- 0.284, P > 0.05), but there was a significant positive correlation with Bcl-2 protein expression ( r = 0.755, P < 0.01). Conclusion:HT-2 toxin may increase the expression of autophagy pathway related protein LC3-Ⅱ/LC3-Ⅰ, decrease the expression of p62 protein, and increase the apoptosis pathway related protein Bax/Bcl-2 by inhibiting the expression of SIRT1 protein in chondrocytes, resulting in abnormal autophagy and apoptosis, and finally leads to the injury of chondrocytes.

Hepatoprotective Effect and Molecular Mechanisms of Hengshun Aromatic Vinegar on Non-Alcoholic Fatty Liver Disease.

Aromatic vinegar with abundant bioactive components can be used as a food additive to assist the treatment of various diseases. However, its effect on non-alcoholic fatty liver disease (NAFLD) is still unknown. The purpose of this study was to investigate the mechanism of Hengshun aromatic vinegar in preventing NAFLD in vivo and in vitro. Aromatic vinegar treatment was applied to rats fed with a high-fat diet (HFD) and HepG2 cells challenged with palmitic acid (PA). Our results showed that aromatic vinegar markedly improved cell viabilities and attenuated cell damage in vitro. The levels of TC, TG, FFA, AST, ALT, and malondialdehyde (MDA) in HFD-induced rats were significantly decreased by aromatic vinegar. Mechanism investigation revealed that aromatic vinegar markedly up-regulated the level of silent information regulator of transcription 1 (Sirt1), and thereby inhibited inflammation of the pathway through down-regulating the expressions of high mobility group box 1, toll-likereceptor-4, nuclear transcription factor-κB, tumor necrosis factor receptor-associated factor-6, and inflammatory factors. Aromatic vinegar simultaneously increased the expression of farnesoid X receptor and suppressed expressions of lipogenesis related proteins, including fatty acid synthase, acetyl-CoA carboxylase-1, sterol regulatory element binding transcription factor 1, and stearoyl-CoA desaturase-1. These results were further validated by knockdown of Sirt1 using siRNAs silencing in vitro. In conclusion, Hengshun aromatic vinegar showed protective effects against NAFLD by enhancing the activity of SIRT1 and thereby inhibiting lipogenesis and inflammation pathways, which is expected to become a new assistant strategy for NAFLD therapy in the future.

Effects of Ginsenoside Rg3 on fatigue resistance and SIRT1 in aged rats.

BACKGROUND: Ginsenoside Rg3 (Rg3) is one of the key components of a frequently used herbal tonic panax ginseng for fatigue treatment. However, the molecular mechanisms of Rg3 on anti-fatigue effects have not been completely understood yet. METHODS AND MATERIALS: We built a postoperative fatigue syndrome (POFS) model and tried to elucidate the molecular mechanisms responsible for anti-fatigue effects of Rg3. 160 aged male rats were randomly divided into four groups (n = 40/group): normal group, Rg3-treated normal group (Rg3 group), postoperative fatigue syndrome model group (POFS group) and Rg3-treated postoperative fatigue syndrome model group (POFS + Rg3 group). The open field test (OFT) was used to assess general activity and exploratory behavior of rats in different groups. We then analyzed total cholesterol (TC), serum triglyceride (TG) and lactate dehydrogenase (LDH) in the blood, as well as superoxide dismutase (SOD), malondialdehyde (MDA), peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) and phosphoenolpyruvate carboxykinase (PEPCK) mRNA expression in skeletal muscles of rats. We also detected the influence of Rg3 on silent information regulator of transcription 1 (sirtuin1, SIRT1) activity and protein 53 (p53) transcriptional activity in vitro. RESULTS: Rg3 significantly increased the journey distance and rearing frequency, while slowed down the rest time. The serum concentrations of TC, TG and LDH were all up-regulated by Rg3. Meanwhile, Rg3 increased concentrations of SOD, but also decreased MDA release out of skeletal muscles. The mRNA expressions of PGC-1α and PEPCK were also enhanced by Rg3. Besides, Rg3 could activate SIRT1 and suppress p53 transcriptional activity in the biological process. DISCUSSION AND CONCLUSION: Rg3 could improve exercise performance and resist fatigue possibly through elevating SIRT1 deacetylase activity.

VDAC1 deacetylation is involved in the protective effects of resveratrol against mitochondria-mediated apoptosis in cardiomyocytes subjected to anoxia/reoxygenation injury.

We have recently demonstrated that Voltage-dependent anion channel 1 (VDAC1), a protein located in the mitochondrial outer membrane, is involved in the effects of resveratrol on the mitochondrial permeability transition pore (mPTP). However, the underlying mechanism of action remains to be elucidated. In the present study, we demonstrated that resveratrol promoted VDAC1 deacetylation in cardiomyocytes in response to anoxia/reoxygenation (A/R) injury. Moreover, silent information regulator of transcription 1 (SIRT1), a NAD+-dependent class III histone deacetylase, was up-regulated after pretreatment with resveratrol. Cells that were treated with Ex527, a specific inhibitor of SIRT1, showed a reduction in both SIRT1 expression and VDAC1 deacetylation, indicating that the deacetylation effect of resveratrol on VDAC1 is mediated by SIRT1. Furthermore, the ability deacetylated VDAC1 to bind to Bax was decreased after pretreatment with resveratrol, whereas Bcl-2 expression changed in the opposite direction. As a result, opening of the mPTP was restrained, the mitochondrial membrane potential was reserved, and cytochrome c release was inhibited, which subsequently decreased cardiomyocyte apoptosis. However, the cardioprotective effects observed after treatment of resveratrol could be abrogated by Ex527. In conclusion, resveratrol induces deacetylation of VDAC1 by SIRT1, thereby preventing mitochondria-mediated apoptosis in cardiomyocytes upon A/R injury.

Effects of Nitric Oxide Synthase Inhibition on Fiber-Type Composition, Mitochondrial Biogenesis, and SIRT1 Expression in Rat Skeletal Muscle.

It was hypothesized that nitric oxide synthases (NOS) regulated SIRT1 expression and lead to a corresponding changes of contractile and metabolic properties in skeletal muscle. The purpose of the present study was to investigate the influence of long-term inhibition of nitric oxide synthases (NOS) on the fiber-type composition, metabolic regulators such as and silent information regulator of transcription 1 (SIRT1) and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), and components of mitochondrial biogenesis in the soleus and plantaris muscles of rats. Rats were assigned to two groups: control and NOS inhibitor (N (ω)-nitro-L-arginine methyl ester hydrochloride (L-NAME), ingested for 8 weeks in drinking water)-treated groups. The percentage of Type I fibers in the L-NAME group was significantly lower than that in the control group, and the percentage of Type IIA fibers was concomitantly higher in soleus muscle. In plantaris muscle, muscle fiber composition was not altered by L-NAME treatment. L-NAME treatment decreased the cytochrome C protein expression and activity of mitochondrial oxidative enzymes in the plantaris muscle but not in soleus muscle. NOS inhibition reduced the SIRT1 protein expression level in both the soleus and plantaris muscles, whereas it did not affect the PGC-1α protein expression. L-NAME treatment also reduced the glucose transporter 4 protein expression in both muscles. These results suggest that NOS plays a role in maintaining SIRT1 protein expression, muscle fiber composition and components of mitochondrial biogenesis in skeletal muscle. Key pointsNOS inhibition by L-NAME treatment decreased the SIRT1 protein expression in skeletal muscle.NOS inhibition induced the Type I to Type IIA fiber type transformation in soleus muscle.NOS inhibition reduced the components of mitochondrial biogenesis and glucose metabolism in skeletal muscle.

Effects and mechanism of silent information regulator of transcription 1 in the drug-resistance of colonic cancer / 中华消化外科杂志

Objective To investigate the effects of mechanism of silent information regulator of transcription 1 (SIRT1) in the drug-resistance of colonic cancer.Methods The clinical data of 25 colonic cancer patients with 5-Fu-resistance and 30 colonic cancer patients with chemosensitivity who were admitted to the Henan Tumor Hospital from December 2012 to December 2013 were retrospectively analyzed.The specimens of colonic cancer were collected for study.(1) The protein expression of SIRT1 in patients with drug-resistance or chemotherapeutic sensitivity was tested by immunohistochemical staining.The protein expression of SIRT1 in the HCT116 and HCT1 16/5-FU cells was detected by Western blot.(2)HCT116/5-FU cells were interfered by siRNA and divided into the blank control group (cells untreated),the empty vector group (cells treated by siRNA) and the SIRT1 silence group (cells treated by SIRT1 siRNA).The protein expression of the HCT116/5-FU cells were inhibited by the c-Jun N-terminal kinase (JNK) and then divided into the SP600125 group [cells were treated by JNK signaling pathway inhibitor SP60012 (concentration:30 μmol/L)for 12 hours],the DMSO group [cells were treated by DMSO (cells were treated by 0.1％ DMSO for 12 hours] and the control group (cells were treated by cell culture media).(3) Serine in the SIRT1 ser47 was mutated to alanine or aspartic acid,and mutations S47A (S47A group,serine to alanine) and S47D (S47D group,serine to aspartic acid) ; Untransfected HCT116/5-FU cells were in the S47 wild type group,and apCMV-3Tag-3 cells transfected by empty vector were served as negative control; all the HCT116/5-FU cells were interfered by 5-FU (concentration:8 μmol/L) for 12 hours.HTC116 cells and HTC116/5-FU cells were treated by SIRT1 inhibitor resveratrol at concentrations of 0,1,10,50,100 nmol/L and SIRT1 activator niacinamide at concentrations of 0,1,2,3,4,5 ng/L.Cell proliferation was detected by MTF.(4) Cell apoptosis was detected by flow cytometry.(5) The expressions of related genes were detected by real-time PCR.(6)The expressions of related proteins were detected by western blot.The count data were analyzed using the chi-square test.The measurement data with normal distribution were presented as (x) ± s.The comparison among groups were analyzed using the one-way analysis of variance and LSD-t test.The pairwise comparisons were analyzed using the t text.Results (1) The results of immunohistochemical staining were as follows.The positive expressions of SIRT1 in patients with chemotherapeutic sensitivity and drug-resistance were 16.7％ (5/30) and 92.0％ (23/25),respectively,with significant difference (x2 =30.965,P ＜ 0.05).The relative mRNA and protein expressions of SIRT1 in HCT116/5-FU cells with drug-resistance were 1.870 ± 0.100 and 1.660 ± 0.109,which were significantly higher than 1.000 ± 0.070 and 1.000 ± 0.050 in HCT116/5-FU cells without drug-resistance (t =11.721,8.963,P ＜ 0.05).(2) The results of MTT were as follows.The proliferation rates of HCT116/5-FU cells treated by resveratrol at concentrations of 0,1,10,50 nmol/L were 100％ ±12％,105％± 14％,129％ ± 10％ and 144％ ± 17％,which were significantly higher than 41％ ± 10％,49％ ±11％,74％ ± 16％ and 105％ ± 17％ of HCT116 cells which were treated by reseratrol at the same contrations (t =8.226,-7.236,6.673,3.510,P ＜0.05).The proliferation rates of HCT116/5-FU cell treated by niacinamide at concentrations of 0,1,2 ng/L were 87％ ± 12％,78％ ± 12％,69％ ± 11％,which were significantly higher than 36％ ± 6％,32％± 5％,30％± 6％ of HCT116 cells which were treated by niacinamide at the same concentrations (t =-8.593,-8.006,-7.000,P ＜ 0.05).The proliferation rates of HCT116/5-FU cells in the blank control group,the empty vector group and the SIRT1 silence group were 100％± 8％,99％ ±9％,37％ ± 6％,with significant differences among the 3 groups (F =66.597,P ＜ 0.05),and the proliferation rate of HCT116/5-FU cells in the SIRT1 silence group was significantly lower than that in the blank control group (t =10.113,P ＜0.05).(3) The results of flow cytometry were as follows.The apoptotic rates of HCT116/5-FU cells in the SIRT1 silence group,the empty vector group and the blank control group were 60％ ± 5％,36％ ± 4％,35％ ±4％,with significant differences among the 3 groups (F =36.549,P ＜ 0.05),and the apoptotic rates of HCT1 16/5-FU cells in the SIRT1 silence group were significantly higher than that in the blank control group and the empty vector group (t =-7.215,-7.084,P ＜0.05).(4)The results of RT-PCR were as follows.The relative expression rates of P-gp mRNA in the HCT116/5-FU cells in the SIRT1 silence group,the empty vector group and the blank control group were 0.320 ± 0.030,0.990 ± 0.060,1.000 ± 0.090,with significant differences among the 3 groups (F =10.107,P ＜ 0.05),and the relative expression rate of P-gp mRNA in the SIRT1 silence group was significantly lower than that in the blank control group (t =11.463,P ＜ 0.05).The relative expression rates of P-gp mRNA in the HCT116/5-FU cells in the SP600125 group,the DMSO group and the control group were 0.240 ±.0.040,0.990 ± 0.100,1.000 ± 0.070,with significant difference among the 3 groups (F =19.002,P＜0.05),and the relative expression rates of P-gp mRNA in the SP600125 group was significantly lower than that in the control group (t =7.301,P ＜0.05).(5) The results of western blot were as follows.The relative expression rates of p-JNK protein in the HCT116/5-FU cells in the blank control group,the empty vector group and the SIRT1 silence group were 1.000 ± 0.090,1.090 ± 0.020,0.080 ± 0.010,with significant difference among the 3 groups (F =12.130,P ＜ 0.05).The ratios of p-SIRT1-S27/T-SIRT1,p-SIRT1-T530/T-SIRT1,p-SIRT1-S47/T-SIRT1 were 1.158 ±0.140,1.209 ±0.150,3.760 ±0.150 in HCT116 cells treated by 5-FU,and 1.120 ±0.109,1.130 ±0.100,2.160 ±0.110 in HCT116 cells treated by DMSO,with significant differences (F =9.763,10.261,P ＜0.05).The ratios of p-SIRT1-S47/T-SIRT1 in HCT116 cells treated by 5-FU and DMSO were 3.760 ± 0.150 and 2.160 ± 0.110,which were significantly higher than 0.940 ± 0.040 and 1.121 ± 0.110 in HCT116/5-FU cells (t =14.721,21.335,P ＜ 0.05).(6) The proliferation rates of HCT116/ 5-FU cells in the S47 wild type group,the negative control group,the S47A group and the S47D group were 41％± 31％,39％ ± 4％,64％ ± 2％ and 26％ ± 5％,with significant differences among the 4 groups (F =6.371,P ＜ 0.05).Conclusions SIRT1 promotes the proliferation of drug-resistant colonic cancer cells and increases the expression of P-gp via JNK signaling pathway,there by enhances cellular drug resistance.SIRT1 S47 is the critical site for 5-FU-resistance in HCT116/5-FU cells.