Salvianolic acid B protects against acute ethanol-induced liver injury through SIRT1-mediated deacetylation of p53 in rats

Salvianolic acid B (SalB) is isolated from the traditional Chinese medical herb salvia miltiorrhiza. It has many biological and pharmaceutical activities. This study aimed to investigate the effect of SalB on acute ethanol-induced hepatic injury in rats and to explore the role of SIRT1 in this process. The results showed that pretreatment with SalB significantly reduced ethanol-induced elevation in aminotransferase activities, decreased hepatotoxic cytokine levels such as Interleukin-6 (IL-6), and increased the antioxidant enzyme activity. Moreover, SalB pretreatment reversed the increase in NF-κB, cleaved caspase-3 and decrease in B-cell lymphoma-extra large (Bcl-xL) caused by ethanol exposure. Importantly, SalB pretreatment significantly increased the expression of SIRT1, a NAD⁺-dependent deacetylase, whereas the increase in SIRT1 was accompanied by decreased acetyl-p53 expression. In HepG2 cells, SalB pretreatment increased SIRT1 expression in a time and dose-dependent manner and such an increase was abrogated by siRNA knockdown of SIRT1. Additionally, inhibition of SIRT1 significantly increased the acetylation of p53, and blocked SalB-induced acetylation of p53 down-regulation. Collectively, this study indicated that SalB can alleviate acute ethanol-induced hepatocyte apoptosis through SIRT1-mediated deacetylation of p53 pathway.     

Combination of chlorogenic acid and salvianolic acid B protects against polychlorinated biphenyls-induced oxidative stress through Nrf2

Caffeic acid derivatives (CADs) are well-known phytochemicals with multiple physiological and pharmacological activities. This study aimed to investigate the combined protective effects of CADs on PCB126-induced liver damages and oxidative stress in mice. Here, we used chemiluminescence and chose chlorogenic acid (CGA), salvianolic acid B (Sal B) as the best antioxidants. Then, mice were intragastrically administered with 60 mg/kg/d CGA, Sal B, and CGA plus Sal B (1:1) for 3 weeks before exposing to 0.05 mg/kg/d PCB126 for 2 weeks. We found that pretreatment with CGA, Sal B, and CGA plus Sal B effectively attenuated liver injury and cytotoxicity caused by PCB126, but improved the expressions of superoxide dismutase (SOD), glutathione reduced (GSH), heme oxygenase-1 (HO-1) and nuclear factor E2-related factor 2 (Nrf2), CGA plus Sal B especially, was found to have the best effects that indicated a synergetic protective effect. Taken together, as the Nrf2 regulates the cyto-protective response by up-regulating the expression of antioxidant genes, we suggested that CGA plus Sal B had a combined protection on PCB126-induced tissue damages and that the Nrf2 signaling might be involved.     

丹酚酸A激活AMPK及SIRT1减轻棕榈酸诱导的肝细胞脂毒性

目的:研究丹酚酸A对棕榈酸诱导的AML12肝细胞脂毒性的保护作用并初步探究其分子机制。方法:采用棕榈酸诱导AML12细胞建立脂毒性模型并给予丹酚酸A进行干预,采用乳酸脱氢酶(LDH)法检测细胞损伤,采用酶法检测细胞内甘油三酯含量,采用Bodipy染色法观察胞内的脂滴,采用甲基偶氮唑盐微量酶反应比色法(MTT)检测细胞存活率,采用荧光细胞通透性染料罗丹明123和荧光显微镜检测线粒体膜电位。采用2',7'-二氯荧光黄双乙酸盐(DCFH-DA)和荧光显微镜检测细胞内活性氧(ROS)水平。采用Western blot技术检测沉默信息调节因子相关酶Ⅰ(silent information regulator 1,SIRT1)及腺苷酸活化蛋白激酶(AMP-activated protein kinase,AMPK)蛋白表达。结果:棕榈酸作为肝细胞脂毒性诱导剂可显著降低AML12细胞存活率,加重细胞内脂质沉积,而丹酚酸A干预可改善棕榈酸诱导的肝细胞脂毒性损伤(P<0.05)。其次,丹酚酸A干预可改善棕榈酸诱导的细胞线粒体膜电位降低(P<0.01)及细胞内ROS水平升高(P<0.01)。此外,Western blot结果显示棕榈酸可显著抑制AMPK及SIRT1蛋白表达(P<0.05),而经过丹酚酸A处理可显著升高棕榈酸抑制的SIRT1及AMPK磷酸化水平(P<0.05)。结论:丹酚酸A可有效改善脂毒性诱导的肝细胞损伤,该保护作用可能与其激活AMPK及SIRT1蛋白有关。     

NAD+-dependent SIRT1 deactivation has a key role on ischemia–reperfusion-induced apoptosis

Ischemia–reperfusion (IR) leads to severe organ injury and dysfunction. Sirtuins (SIRTs) are a family of histone deacetylases (HDACs) that require nicotinamide adenine dinucleotide (NAD⁺) for the deacetylation reaction. SIRTs play a major role in counteracting cellular stress and apoptosis. This study aimed to investigate the mechanisms of heart protection against apoptosis by SIRTs and the molecular pathways involved in SIRTs regulation and function in a rat model of IR injury.Hearts of male Wistar–Kyoto rats were subjected to 30-min ischemia followed by reperfusion up to 6 h. IR increased cardiomyocyte apoptosis; the cleavage of caspase 3, induced a transient upregulation of SIRT1 and downregulation of SIRT6 expression, but decreased SIRT1 activity and reduced NAD⁺ content. IR also increased forkhead box protein O1 (FoxO1) expression and FoxO1 binding to SIRT1 promoter region. Resveratrol restored SIRT1 activity and NAD⁺ level by an AMPK-dependent mechanism, reduced cardiomyocyte apoptosis, and attenuated caspase 3 cleavage via heat shock factor-1 deacetylation and heat shock protein (HSP) expression upregulation.Our data show new potential molecular mechanisms of up and downstream regulation of SIRT1 in IR. The interplay among FoxO1, SIRT1, NAD⁺, AMPK, HSP, and SIRT6 depicts a complex molecular network that protects the heart from apoptosis during IR and may be susceptible to therapeutic interventions.     

Amiodarone induces autophagy/mitophagy by activating sirtuin-3 in acute myelocytic leukemia

OBJECTIVE To find a new treatment strategy foracute myelocytic leukemia(AML), we tried to find new targets. Sirtuin-3(SIRT3), a NAD+-dependent protein deacetylase localized primarily in the mitochondrion,is well-known to regulate autophagy, which is an evolutionarily conserved, multi-step lysosomal degradation process and also implicated in many diseases, such as AML.Accumulating evidence has revealed that SIRT3 may act as a tumor suppressor in AML, and thus activating SIRT3 will represent a potential therapeutic avenue.METHODS Aotophagy related protein expression and SIRT3 were analyzed by The Cancer Genome Atlas(TCGA)analysis. SIRT3 activator was selected by using in silico screening and anti-proliferative activities. The target selectivity of amiodarone was determined by co-crystal structure and deacetylase activity assays. The mechanisms of amiodarone-induced autophagy/mitophagy were investigated by fluorescence microscope, Western blotting, flow cytometry analysis, immunocytochemistry, as well as i TRAQ-based proteomics analysis. The therapeutic effect of amiodarone was assessed by xenograft AML mouse model. RESULTS TCGA dataset, we identified that SIRT3 was a key prognostic factor in AML, which was closely associated with the survival of patients. Subsequently, we computationally and experimentally screened a series of candidate activators of SIRT3 from Drugbank,and found the best candidate compound amiodarone,which was further validated by co-crystal structure of SIRT3/amiodarone. Interestingly, amiodarone induced autophagy via SIRT3-mediated AMPK-m TOR-ULK1-Beclin-1 pathway in U937 and HL-60 cells. Moreover,this activator induced mitophagy via SIRT3-deacetylating FOXO3 a and thus triggering PINK1/Parkin pathway in AML cells. The i TRAQ-based proteomics analyses revealed that amiodarone induced mitophagy by downregulating 14-3-3γ, upregulating and deacetylating Beclin-1,as well as activating FOXO3 a-HIF1α-BNIP3 and VDAC1.What is more, deacetylation proteomics analyses revealed that amiodarone could activate SIRT3 to deacetylate EIF3 a and PGAM5 to inhibit ERK1/2 signaling and activate FUNDC1-LC3. Furthermore, we found that amiodarone had a therapeutic potential on AML and induced autophagy/mitophagy by activating SIRT3 in vivo. CONCLUSION Together, these results demonstrate a novel potent and targeted SIRT3 activator, amiodarone that induces autophagy/mitophagy in AML, which would be utilized to for future drug development.     

Differential inhibitory effects of salvianolic acids on activation of rat hepatic stellate cells by platelet-derived growth factor

Platelet-derived growth factor (PDGF) induces cell proliferation together with oxidative stress. The present study investigated the effects of salvianolic acid A (Sal A) and B (Sal B) on the PDGF-induced signaling cascades in hepatic stellate cells (HSCs). HSC-T6, a rat hepatic stellate cell line, was stimulated with PDGF (10?ng/mL). The inhibitory effects of Sal A and B on oxidative stress-related signaling pathways were assessed in vitro. The protein levels were measured by Western blotting. FACS analysis was applied to detect the thioredoxin (Trx) level. Sal A and B showed different inhibitory abilities on the PDGF-related pathway. Sal A inhibited 70-kDa ribosomal S6 kinase (p70(s6k)) and associated proteins. Sal B attenuated PDGF-induced c-jun-N-terminal kinase (JNK), p38, and PKC- δ phosphorylations. Both Sal A and B diminished the activation of PKD, Trx, heme-oxygenase (HO)-1, and Nrf2. Taken together, our results showed that Sal A and B attenuated PDGF-induced ROS formation in HSCs, possibly through different signaling pathways.     

Metformin inhibits high glucose‐induced mesangial cell proliferation,inflammation and ECM expression through the SIRT1‐FOXO1‐autophagy axis

The aim of this study was to investigate the role of metformin in high glucose‐induced mesangial cell proliferation, inflammation and extracellular matrix (ECM) accumulation and to elucidate the underlying mechanism of metformin function. An MTT assay was used to examine rat mesangial cell (RMC) proliferation. The levels of TNF‐α, IL‐6 and TGF‐β in RMCs were determined by ELISA. The protein expression of fibronectin, collagen IV and autophagy‐related proteins (Beclin‐1, LC3‐I and LC3‐II) in RMCs was detected using western blot. Fluorescence microscopy analysis was carried out to evaluate RMC autophagy. Our results showed that high glucose‐induced RMC proliferation, inflammation and ECM expression, but these effects were markedly reduced by metformin. We confirmed that metformin suppressed high glucose‐induced RMC proliferation, inflammation and ECM expression via induction of autophagy. Mechanistic investigation demonstrated an axis of SIRT1‐FOXO1 in RMC autophagy. Our data indicated that metformin inhibits high glucose‐induced mesangial cell proliferation, inflammation and ECM expression through a SIRT1‐FOXO1‐autophagy axis.     

Chlorogenic acid protects MSCs against oxidative stress by altering FOXO family genes and activating intrinsic pathway

Chlorogenic acid as an antioxidant exists widely in edible and medicinal plants, and can protect cell against apoptosis induced by oxidative stress. However, its molecular mechanisms remain largely unknown. Here, we showed that Chlorogenic acid suppressed reactive oxygen species increase by activation of Akt phosphorylation,and increased FOXO family genes and anti-apoptotic protein Bcl-2 expression in MSCs culturing under oxidative stress. In addition, PI-3Kinase Inhibitor (2-(4-Morpholinyl)-8-phenyl-4H-1-benzopyran-4-one, LY294002) could suppress the Chlorogenic acid-induced: (1) the cellular protective role, (2) the increase of the FOXO family genes expression, (3) increased expression of Bcl-2. These results suggested that Chlorogenic acid protected MSCs against apoptosis via PI3K/AKT signal and FOXO family genes.     

Exendin-4 exhibits a tumour suppressor effect in SKOVR-3 and OVACR-3 ovarian cancer cells lines by the activation of SIRT1 and inhibition of NF-κB

This study investigated if EX-527 has an anti-tumour effect in SKOV-3 and OVCAR-3 ovarian cancer (OC) cell lines and if this effect involves the SIRT1/NF-κB axis. Cells were cultured in the presence or absence of EX-527, a selective SIRT-1 inhibitor. Exendin-4 significantly induced cell death in both cell lines and inhibited cell migration and invasion. Also, it decreased protein levels of Bcl-2, MMP-9, and ICAM-1 and increased those of Bax, cyclin D1 and cleaved caspase-3. Mechanistically, Exendin-4 increased the activity and nuclear accumulation of SIRT1 and decreased nuclear levels of NF-κB p65; acetylated levels of NF-κB p65, and cytoplasmic levels of p-IKKα and p-IκBα. EX-527 partially ameliorated the effect of Exendin-4 on cell death, migration, and invasion, as well as on the expression of Bcl-2, MMP-9, Bax, cleaved caspase-3 and ICAM-1. In addition, EX-527 did not affect the levels of nuclear p65 and p-p65 (Ser536); p-IκBα (Ser32) and p-IKKαβ. In conclusion, Exendin-4 can suppress OC by inhibiting NF-kB through SIRT1 dependent and independent mechanisms.     

丹酚酸B在剪切应激存在下对血管内皮细胞ICAM-1的影响

目的：观察丹酚酸B（SalB）在不同强度血流剪切应激下对血管内皮细胞ICAM-1的影响。方法：首先建立层流剪切应激（LSS）模型,利用蛋白质化学印迹Westernblot检测不同剪切时间（1、4、24h）对血管内皮细胞表达的细胞内黏附因子ICAM-1的影响;其次利用Westernblot方法检测不同浓度（0、5、10、25、50μg·mL-1）SalB处理内皮细胞后ICAM-1的表达情况;最后血管内皮细胞先用10μg·mL-1SalB预处理24h后,加入LSS[12dynes·（cm2）-1]的剪切应激12h,观察丹酚酸B（SalB）在剪切应激存在下对内皮细胞所表达的ICAM-1的影响。结果：我们发现不同剪切时间（1、4、24h）的LSS[12dynes·（cm2）-1]可呈时间依赖性增加ICAM-1的表达,SalB可呈浓度依赖性降低剪切应激诱导的ICAM-1的表达,这一降低可能是通过NF-κB信号转导途径介导实施的。结论：SalB可通过NF-κB信号转导途径降低LSS诱导的ICAM-1的增高。     

Resveratrol inhibits interleukin 1β-mediated inducible nitric oxide synthase expression in articular chondrocytes by activating SIRT1 and thereby suppressing nuclear factor-κB activity

In chondrocytes, resveratrol, a natural SIRT1 activator, exerts an anti-inflammatory response via inhibition of nuclear factor kappaB (NF-κB). Given that SIRT1 inhibits the transactivation potential of NF-κB by deacetylating acetylated lysines in p65, the NF-κB subunit, we investigated the effects of resveratrol-activated SIRT1 on articular chondrocytes. We found that when chondrocytes were stimulated with interleukin 1β (IL-1β), the time- and dose-dependent expression of inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) production was suppressed by resveratrol. Resveratrol-activated SIRT1 mediated this suppression. SIRT1 suppressed not only the nuclear translocation of NF-κB but also the acetylation of p65. Furthermore, acetylated Lys310 in p65, which must be present for transactivation activity, was the immediate downstream target of SIRT1. Therefore, SIRT1 protects against the inflammatory response induced by IL-1β in articular chondrocytes. Resveratrol, as an activator of SIRT1, merits consideration as a therapeutic agent in the treatment and prevention of osteoarthritis.     

Pretreatment with Tilianin improves mitochondrial energy metabolism and oxidative stress in rats with myocardial ischemia/reperfusion injury via AMPK/SIRT1/PGC-1 alpha signaling pathway

Mitochondrial energy metabolism and oxidative stress play a crucial role in ameliorating myocardial ischemia/reperfusion injury (MIRI). Tilianin has been reported to have a significant protection for mitochondrion in MIRI. However, the underlying mechanisms remain unknown. This study investigated whether Tilianin regulates mitochondrial energy metabolism and oxidative stress in MIRI via AMPK/SIRT1/PGC-1 alpha signaling pathway. The MIRI model was established by 30 min of coronary occlusion followed by 2 h of reperfusion in rats. The results revealed that Tilianin significantly reduced myocardial infarction, improved the pathological morphology of myocardium, markedly increased the contents of ATP and NAD⁺, decreased ADP and AMP contents and the ratio of AMP/ATP, reduced the level of ROS and MDA, enhanced SOD activity, evidently increased the levels of AMPK, SIRT1 and PGC-1 alpha mRNA, up-regulated the expressions of AMPK, pAMPK, SIRT1, PGC-1alpha, NRF1, TFAM and FOXO1 proteins. However, these effects were respectively abolished by Compound C (a specific AMPK inhibitor) and EX-527 (a specific SIRT1 inhibitor). Taken together, this study found that Tilianin could attenuate MIRI by improving mitochondrial energy metabolism and reducing oxidative stress via AMPK/SIRT1/PGC-1 alpha signaling pathway.     

丹酚酸B对MC3T3-E1细胞Dkk1 mRNA表达的影响

目的:观察丹酚酸B对MC3T3-E1细胞Dkk1mRNA表达的影响。方法:MC3T3-E1细胞分组:正常对照组、成骨诱导组、地塞米松1×10-6 mol·L-1组、地塞米松1×10-6 mol·L-1+丹酚酸B1×10-7 mol·L-1组、地塞米松1×10-6 mol·L-1+Dkk1抗体100μg·L-1组、丹酚酸B1×10-7 mol·L-1组、Dkk1抗体100μg·L-1组。加药7 d后用RT-PCR法检测细胞Dkk1mRNA表达水平。结果:与正常组相比,成骨诱导后Dkk1的表达增多,地塞米松组的Dkk1表达明显增多,丹酚酸B组Dkk1的表达减少,Dkk1抗体单用未见Dkk1的表达。与地塞米松组相比,丹酚酸B单用Dkk1的表达比地塞米松组少。丹酚酸B、Dkk1抗体可对抗地塞米松应用后引起的Dkk1表达增多。结论:丹酚酸B可以减少Dkk1的表达和对抗地塞米松使用后引起的Dkk1表达增多,这可能是其促骨形成的机制之一。     

Effects of salvianolic acids on oxidative stress and hepatic fibrosis in rats

Enhanced oxidative stress is associated with hepatic fibrosis. Salvianolic acids A (Sal A) and B (Sal B) have been reported to be strong polyphenolic antioxidants and free radical scavengers. The present study is to investigate if Sal A and B could attenuate oxidative stress and liver fibrosis in rats. A cell line of rat hepatic stellate cells (HSCs) was stimulated with platelet-derived growth factor (PDGF, 10 ng/ml). The inhibitory effects of Sal A and B on intracellular hydrogen peroxide levels were measured with dichlorofluorescein diacetate (DCF-DA) dye assay. α-Smooth muscle actin (α-SMA), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits were measured by Western blotting. Liver fibrosis was induced by intraperitoneal injections of thioacetamide (TAA, 200 mg/kg) twice per week for 6 weeks. Sal A (10 mg/kg), Sal B (50 mg/kg) or S-adenosylmethionine (SAMe, 10 mg/kg), was given by gavage twice per day consecutively for 4 weeks starting 2 weeks after TAA injection. In vitro, PDGF increased the accumulation of hydrogen peroxide in HSCs, which was attenuated by Sal A (10 μM) and Sal B (200 μM). Sal A and B attenuated the PDGF-stimulated expressions of α-SMA and NADPH oxidase subunits gp91^phox and p47^phox in membrane fractions. In vivo studies showed that the hepatic levels of collagen, malondialdehyde, TNF-α, IL-6, and IL-1β, fibrosis scores and protein expressions of α-SMA, heme-oxygenase-1, iNOS, and gp91^phox, and serum levels of ALT, AST, IL-6, and IL-1β were increased in TAA-intoxicated rats, all of which were attenuated by 4-week treatment of Sal A or Sal B. Our results showed that Sal A and B attenuated PDGF-induced ROS formation in HSCs, possibly through inhibition of NADPH oxidase. Sal A and B treatments were also effective against hepatic fibrosis in TAA-intoxicated rats.     

Pharmacokinetic interactions induced by content variation of major water-soluble components of Danshen preparation in rats

Aim:

To investigate the pharmacokinetic interactions induced by content variation of the main water-soluble components of Danshen injection in rats.

Methods:

Intravenous Danshen injection (control) or Danshen injection with danshensu (DSS), protocatechuic aldehyde (PAL), salvianolic acid A (Sal A) or salvianolic acid B (Sal B) were administered to female Sprague Dawley rats . Plasma concentrations of DSS, Sal A, PAL and its oxidative metabolite protocatechuic acid (PA) were analyzed simultaneously with LC-MS/MS; concentrations of Sal B were determined by the LC-MS method. Non-compartmental pharmacokinetic parameters were calculated and compared for identifying the pharmacokinetic interactions among these components.

Results:

Compared with the control group, the DSS, Sal A, and Sal B groups had significant increases in AUC_0-∞ in response to elevated concentrations of PAL (by 78.1%, 51.0%, and 82.9%, respectively), while the clearances (CL) were markedly reduced (by 42.5%, 32.9%, and 46.8%, respectively). Similarly, Sal A increased the AUC_0–∞ of DSS and Sal B (26.7% and 82.4%, respectively) and substantially decreased their clearances (21.4% and 45.6%, respectively). In addition, the pharmacokinetics of DSS and Sal B were significantly affected by the content variation of the other major components; the AUC_0-∞ increased by 45.1% and 52.1%, respectively, the CL dropped by 29.6% and 27.1%, respectively, and the T_1/2 was decreased by 22.0% and 19.6%, respectively.

Conclusion:

Complex, extensive pharmacokinetic interactions were observed among the major water-soluble constituents in the Danshen injection. The content variation of PAL had the most significant effect on the pharmacokinetic behaviors of other major constituents. Furthermore, the pharmacokinetics of DSS and Sal B were the most susceptible to the content change of other components.     

G protein-coupled receptor 35 attenuates nonalcoholic steatohepatitis by reprogramming cholesterol homeostasis in hepatocytes

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. Fat accumulation “sensitizes” the liver to insult and leads to nonalcoholic steatohepatitis (NASH). G protein-coupled receptor 35 (GPR35) is involved in metabolic stresses, but its role in NAFLD is unknown. We report that hepatocyte GPR35 mitigates NASH by regulating hepatic cholesterol homeostasis. Specifically, we found that GPR35 overexpression in hepatocytes protected against high-fat/cholesterol/fructose (HFCF) diet-induced steatohepatitis, whereas loss of GPR35 had the opposite effect. Administration of the GPR35 agonist kynurenic acid (Kyna) suppressed HFCF diet-induced steatohepatitis in mice. Kyna/GPR35 induced expression of StAR-related lipid transfer protein 4 (STARD4) through the ERK1/2 signaling pathway, ultimately resulting in hepatic cholesterol esterification and bile acid synthesis (BAS). The overexpression of STARD4 increased the expression of the BAS rate-limiting enzymes cytochrome P450 family 7 subfamily A member 1 (CYP7A1) and CYP8B1, promoting the conversion of cholesterol to bile acid. The protective effect induced by GPR35 overexpression in hepatocytes disappeared in hepatocyte STARD4-knockdown mice. STARD4 overexpression in hepatocytes reversed the aggravation of HFCF diet-induced steatohepatitis caused by the loss of GPR35 expression in hepatocytes in mice. Our findings indicate that the GPR35–STARD4 axis is a promising therapeutic target for NAFLD.