Silent information regulator sirtuin 1 ameliorates acute liver failure via the p53/glutathione peroxidase 4/gasdermin D axis

BACKGROUND Acute liver failure(ALF)has a high mortality with widespread hepatocyte death involving ferroptosis and pyroptosis.The silent information regulator sirtuin 1(SIRT1)-mediated deacetylation affects multiple biological processes,including cellular senescence,apoptosis,sugar and lipid metabolism,oxidative stress,and inflammation.AIM To investigate the association between ferroptosis and pyroptosis and the upstream regulatory mechanisms.METHODS This study included 30 patients with ALF and 30 healthy individuals who underwent serum alanine aminotransferase(ALT)and aspartate aminotransferase(AST)testing.C57BL/6 mice were also intraperitoneally pretreated with SIRT1,p53,or glutathione peroxidase 4(GPX4)inducers and inhibitors and injected with lipopolysaccharide(LPS)/D-galactosamine(D-GalN)to induce ALF.Gasdermin D(GSDMD)^(-/-)mice were used as an experimental group.Histological changes in liver tissue were monitored by hematoxylin and eosin staining.ALT,AST,glutathione,reactive oxygen species,and iron levels were measured using commercial kits.Ferroptosis-and pyroptosis-related protein and mRNA expression was detected by western blot and quantitative real-time polymerase chain reaction.SIRT1,p53,and GSDMD were assessed by immunofluorescence analysis.RESULTS Serum AST and ALT levels were elevated in patients with ALF.SIRT1,solute carrier family 7a member 11(SLC7A11),and GPX4 protein expression was decreased and acetylated p5,p53,GSDMD,and acyl-CoA synthetase long-chain family member 4(ACSL4)protein levels were elevated in human ALF liver tissue.In the p53 and ferroptosis inhibitor-treated and GSDMD^(-/-)groups,serum interleukin(IL)-1β,tumour necrosis factor alpha,IL-6,IL-2 and C-C motif ligand 2 levels were decreased and hepatic impairment was mitigated.In mice with GSDMD knockout,p53 was reduced,GPX4 was increased,and ferroptotic events(depletion of SLC7A11,elevation of ACSL4,and iron accumulation)were detected.In vitro,knockdown of p53 and overexpression of GPX4 reduced AST and ALT levels,the cytostatic rate,and GSDMD expression,restoring SLC7A11 depletion.Moreover,SIRT1 agonist and overexpression of SIRT1 alleviated acute liver injury and decreased iron deposition compared with results in the model group,accompanied by reduced p53,GSDMD,and ACSL4,and increased SLC7A11 and GPX4.Inactivation of SIRT1 exacerbated ferroptotic and pyroptotic cell death and aggravated liver injury in LPS/D-GalNinduced in vitro and in vivo models.CONCLUSION SIRT1 activation attenuates LPS/D-GalN-induced ferroptosis and pyroptosis by inhibiting the p53/GPX4/GSDMD signaling pathway in ALF.

Hydrogen-rich water alleviates constipation by attenuating oxidative stress through the sirtuin1/nuclear factor-erythroid-2-related factor 2/heme oxygenase-1 signaling pathway

BACKGROUND Constipation,a highly prevalent functional gastrointestinal disorder,induces a significant burden on the quality of patients'life and is associated with substantial healthcare expenditures.Therefore,identifying efficient therapeutic modalities for constipation is of paramount importance.Oxidative stress is a pivotal contributor to colonic dysmotility and is the underlying pathology responsible for constipation symptoms.Consequently,we postulate that hydrogen therapy,an emerging and promising intervention,can serve as a safe and efficacious treatment for constipation.AIM To determine whether hydrogen-rich water(HRW)alleviates constipation and its potential mechanism.METHODS Constipation models were established by orally loperamide to Sprague-Dawley rats.Rats freely consumed HRW,and were recorded their 24 h total stool weight,fecal water content,and charcoal propulsion rate.Fecal samples were subjected to 16S rDNA gene sequencing.Serum non-targeted metabolomic analysis,malondialdehyde,and superoxide dismutase levels were determined.Colonic tissues were stained with hematoxylin and eosin,Alcian blue-periodic acid-Schiff,reactive oxygen species(ROS)immunofluorescence,and immunohistochemistry for cell growth factor receptor kit(c-kit),PGP 9.5,sirtuin1(SIRT1),nuclear factor-erythroid-2-related factor 2(Nrf2),and heme oxygenase-1(HO-1).Quantitative real-time PCR and western blot analysis were conducted to determine the expression level of SIRT1,Nrf2 and HO-1.A rescue experiment was conducted by intraperitoneally injecting the SIRT1 inhibitor,EX527,into constipated rats.NCM460 cells were induced with H2O2 and treated with the metabolites to evaluate ROS and SIRT1 expression.RESULTS HRW alleviated constipation symptoms by improving the total amount of stool over 24 h,fecal water content,charcoal propulsion rate,thickness of the intestinal mucus layer,c-kit expression,and the number of intestinal neurons.HRW modulated intestinal microbiota imbalance and abnormalities in serum metabolism.HRW could also reduce intestinal oxidative stress through the SIRT1/Nrf2/HO-1 signaling pathway.This regulatory effect on oxidative stress was confirmed via an intraperitoneal injection of a SIRT1 inhibitor to constipated rats.The serum metabolites,β-leucine(β-Leu)and traumatic acid,were also found to attenuate H2O2-induced oxidative stress in NCM460 cells by up-regulating SIRT1.CONCLUSION HRW attenuates constipation-associated intestinal oxidative stress via SIRT1/Nrf2/HO-1 signaling pathway,modulating gut microbiota and serum metabolites.β-Leu and traumatic acid are potential metabolites that upregulate SIRT1 expression and reduce oxidative stress.

Thrombopoietin ameliorates doxorubicin-induced toxicities in H9c2 myocardiocytes by inhibiting oxidative stress through the SIRT1/p38 MAPK signaling pathway

Objective:To explore whether thrombopoietin can exert a protective effect against doxorubicin-induced cardiotoxicity by modulating the sirtuin 1(SIRT1)signaling pathway.Methods:H9c2 cell viability was determined by CCK-8 and cardiomyocyte apoptosis was detected by TUNEL assay.The protein expressions of SIRT1 and p38 MAPK were measured by Western blot.RT-qPCR was also used to determine SIRT1 mRNA expression.In addition,intracellular reactive oxygen species levels and antioxidant enzyme activities were evaluated.Results:Thrombopoietin treatment reversed doxorubicin-induced decline in H9c2 cell viability.It also increased SIRT1 and decreased p-p38 MAPK protein expressions.In addition,thrombopoietin significantly attenuated doxorubicin-induced apoptosis and oxidative stress,and enhanced antioxidant enzyme activities.However,silencing SIRT1 abrogated the protective effects of thrombopoietin,as evidenced by reduced cell viability and increased oxidative stress and reactive oxygen species levels.Conclusions:Thrombopoietin alleviates doxorubicin-induced cardiomyocyte injury by reducing oxidative stress and apoptosis via the SIRT1/p38 MAPK pathway.However,its protective effects need to be further verified in animal tests.

Sirtuin 1 in regulating the p53/glutathione peroxidase 4/gasdermin D axis in acute liver failure

In this editorial,we comment on the article by Zhou et al.The study reveals the connection between ferroptosis and pyroptosis and the effect of silent information regulator sirtuin 1(SIRT1)activation in acute liver failure(ALF).ALF is characterized by a sudden and severe liver injury resulting in significant hepatocyte damage,often posing a high risk of mortality.The predominant form of hepatic cell death in ALF involves apoptosis,ferroptosis,autophagy,pyroptosis,and necroptosis.Glutathione peroxidase 4(GPX4)inhibition sensitizes the cell to ferroptosis and triggers cell death,while Gasdermin D(GSDMD)is a mediator of pyroptosis.The study showed that ferroptosis and pyroptosis in ALF are regulated by blocking the p53/GPX4/GSDMD pathway,bridging the gap between the two processes.The inhibition of p53 elevates the levels of GPX4,reducing the levels of inflammatory and liver injury markers,ferroptotic events,and GSDMDN protein levels.Reduced p53 expression and increased GPX4 on deletion of GSDMD indicated ferroptosis and pyroptosis interaction.SIRT1 is a NAD-dependent deacetylase,and its activation attenuates liver injury and inflammation,accompanied by reduced ferroptosis and pyroptosis-related proteins in ALF.SIRT1 activation also inhibits the p53/GPX4/GSDMD axis by inducing p53 acetylation,attenuating LPS/D-GalN-induced ALF.

Circular RNA circ_0003609 ameliorates hypertrophied ligamentum flavum by regulating the miR-155/SIRT1 axis

Background:Hypertrophy of the ligamentumflavum(HLF)is a common contributor to spinal stenosis which results in significant neurological impairments.Circular RNA(circRNA)circ_0003609 has been linked to HLF;however,the exact mechanism by which it causes this disease is unclear.Methods:Circ_0003609 expressions were regulated in HLF cells by overexpression vectors and RNA interference.Cell proliferation andfibrosis-related gene expression were checked by the Cell Counting Kit-8(CCK-8)assay and western blotting.CircBank’s prediction of the association between miR-155 and circ_0003609 was supported by a dual-luciferase reporter experiment.The function of the miR-155/sirtuin 1(SIRT1)axis in controlling HLFfibrosis was further examined.Results:Overexpression of circ_0003609 suppressed HLF cell propagation andfibrosis compared to its silencing.It was found that circ_0003609 served as the sponge for miR-155 and that the circ_0003609/miR-155 axis controlled thefibrosis of HLF cells.It was found that circ_0003609 acted as a sponge for miR-155,regulating thefibrosis of HLF cells.Further,miR-155 targets SIRT1,and the miR-155/SIRT1 axis promotes HLF cellfibrosis.Conclusion:Circ_0003609 ameliorates hypertrophied ligamentumflavum(LF)by modulating the miR-155/SIRT1 axis,indicating a potential treatment approach for HLF.

抑制miR-34a减少高糖代谢记忆所致视网膜色素上皮细胞SIRT1下调和凋亡

目的探讨mi R-34a在视网膜色素上皮(retinal pigment epithelium,RPE)细胞高糖"代谢记忆"中的作用及其机制,为糖尿病视网膜病的防治提供新的策略。方法 RPE细胞用高糖培养4d后换用正常糖浓度培养4d,模拟糖尿病高糖代谢记忆模型,用mi R-34a mimic和mi R-34a inhibitor改变高糖代谢记忆RPE细胞内mi R-34a表达,实时定量PCR检测mi R-34a表达水平,免疫细胞化学和Western blot检测组蛋白去乙酰化酶Sirtuin 1(SIRT1)水平,annexin V-PI法流式细胞术检测细胞凋亡。结果实时定量PCR检测显示,高糖培养和代谢记忆可显著升高RPE细胞内mi R-34a表达水平,mi R-34a mimic可进一步显著上调代谢记忆RPE细胞内mi R-34a表达水平,mi R-34a inhibitor可显著下调代谢记忆RPE细胞内mi R-34a水平;免疫细胞化学染色显示,高糖培养和代谢记忆可使RPE细胞内STRT1免疫反应性显著降低,过表达mi R-34a进一步下调代谢记忆RPE细胞内STRT1免疫反应性,而mi R-34a inhibitor则可抑制代谢记忆对RPE细胞内STRT1免疫反应性的下调作用;流式细胞术检测发现,高糖培养和代谢记忆使RPE细胞凋亡明显增加,过表达mi R-34a进一步增加代谢记忆RPE细胞凋亡,而mi R-34a inhibitor则显著抑制代谢记忆RPE细胞凋亡的增加。结论 mi R-34a抑制剂能通过抑制高糖代谢记忆对RPE细胞SIRT1水平的下调和细胞凋亡的增加,部分逆转高糖代谢记忆效应,防治糖尿病视网膜病变。

SIRT-1在不同宫颈组织中的表达及其临床意义

目的:探讨Ⅲ型去乙酰化酶SIRTUIN1(SIRT-1)蛋白在正常宫颈组织及不同级别宫颈病变组织中的表达及其临床意义。方法:应用Western-blot方法及免疫组化(SP)法检测正常宫颈组织(24例)、低级别鳞状上皮内病变组织(LSIL)26例、高级别鳞状上皮内病变组织(HSIL)35例及宫颈癌组织55例中SIRT-1蛋白的表达情况;并分析SIRT-1蛋白的表达与宫颈癌组织各临床病理参数间的关系。结果:(1)SIRT-1蛋白的高表达率在正常宫颈组织为0、LSIL为15.38%、HSIL为37.14%及宫颈癌组织为40.00%,差异有统计学意义(χ~2=16.82,P<0.05);(2)宫颈癌组织中SIRT-1蛋白的高表达率在不同组织学分化程度(G1~G3)(χ~2=6.87,P<0.05)、有无淋巴结转移(χ~2=7.73,P<0.05)、不同临床分期(χ~2=7.39,P<0.05)间差异均有统计学意义。结论:SIRT-1随宫颈病变的加重表达逐渐增强,与宫颈癌组织学分化程度、有无淋巴结转移、临床分期有关。可能在宫颈癌的发生和发展过程中起促进作用。

Hippocampal insulin resistance and the Sirtuin 1 signaling pathway in diabetes-induced cognitive dysfunction

In the peripheral nervous system,the activation of Sirtuin 1 can improve insulin resistance;however,the role played by Sirtuin 1 in the central nervous system remains unknown.In this study,rat models of diabetes mellitus were generated by a single injection of streptozotocin.At 8 weeks after streptozotocin injection,the Morris water maze test and western blot assays confirmed that the diabetic model rats had learning and memory deficits,insulin resistance,and Sirtuin 1 expression could be detected in the hippocampus.Insulin and the insulin receptor inhibitor S961 were intranasally administered to investigate the regulatory effects of insulin signaling on Sirtuin 1.The results showed that insulin administration improved the impaired cognitive function of diabetic model rats and increased the expression levels of phosphorylated insulin receptor,phosphorylated insulin receptor substrate 1,and Sirtuin 1 in the hippocampus.Conversely,S961 administration resulted in more severe cognitive dysfunction and reduced the expression levels of phosphorylated insulin receptor,phosphorylated insulin receptor substrate 1,and Sirtuin 1.The Sirtuin 1 activator SRT2104 and the inhibitor Sirtinol were injected into the lateral ventricle,which revealed that the activation of Sirtuin 1 increased the expression levels of target of rapamycin complex 1,phosphorylated cAMP-response elementbinding protein,and brain-derived neurotrophic factor.Hippocampal dendritic length and spine density also increased in response to Sirtuin 1 activation.In contrast,Sirtinol decreased the expression levels of target of rapamycin complex 1,phosphorylated cAMP-response elementbinding protein,and brain-derived neurotrophic factor and damaged the dendritic structure.These findings suggest that the Sirtuin 1 signaling pathway plays an important role in the development of insulin resistance-related cognitive deficits in diabetic rats.This study was approved by the Animal Ethics Welfare Committee of the First Affiliated Hospital of Hunan University of Chinese Medicine(approval No.ZYFY201811207)in November 2018.

组蛋白去乙酰化酶SIRT1促进P19CL6细胞向心肌细胞分化

目的探讨Ⅲ类组蛋白去乙酰化酶SIRT1对二甲亚砜(DMSO)诱导的P19CL6细胞向心肌细胞分化的作用。方法以稳定表达SIRT1及负显性突变体SIRT1H363Y的P19CL6细胞为实验组,稳定表达pcDNA3.1载体及空白P19CL6细胞为对照组。1%DMSO诱导细胞分化,在诱导后0、4、8、12d,分别收取细胞,以RealtimePCR检测心脏特异性转录因子NKX2.5、GATA4和心脏功能蛋白a-MHC、ANP的表达。结果 SIRT1过表达使P19CL6细胞在分化过程中心脏特异性转录因子及功能蛋白的表达与对照相比均提前及升高,而负显性突变体SIRT1H363Y过表达使P19CL6细胞在分化过程中标志蛋白的表达与对照相比出现明显滞后和降低。结论 SIRT1促进DMSO诱导的P19CL6细胞向心肌细胞分化。

Resveratrol-downregulated Phosphorylated Liver Kinase B1 Is Involved in Senescence of Acute Myeloid Leukemia Stem Cells

Summary： Senescence is an important obstacle to cancer development. Engaging a senescent response may be an effective way to cure acute myeloid leukemia （AML）. The aim of this study was to examine the effect of resveratrol-downregulated phosphorylated liver kinase B1 （pLKB1） on the senescence of acute myeloid leukemia （AML） stem cells. The protein expressions of pLKB 1 and Sirtuin 1 （SIRT1）, a regulator ofpLKB1, were measured in CD34＋CD38-KGla cells treated with resveratrol （40 μmol/L） or not by Western blotting. Senescence-related factors were examined, including p21 mRNA tested by real-time PCR, cell morphology by senescence-associated β-galactosidase （SA-β-gal） staining, cell pro- liferation by MTT assay and cell cycle by flow cytometry. Besides, apoptosis was flow cytometrically determined. The results showed that pLKB1 was highly expressed in CD34＋CD38- KGla cells, and resveratrol, which could downregulate pLKB1 through activation of SIRT1, induced senescence and apoptosis of CD34＋CD38- KGla cells. It was concluded that resveratrol-downregulated pLKB1 is in- volved in the senescence of AML stem cells.

Effects of natural mineral-rich water consumption on the expression of sirtuin 1 and angiogenic factors in the erectile tissue of rats with fructose-induced metabolic syndrome

Consuming a high-fructose diet induces metabolic syndrome （MS）-Iike features, including endothelial dysfunction. Erectile dysfunction is an early manifestation of endothelial dysfunction and systemic vascular disease. Because mineral deficiency intensifies the deleterious effects of fructose consumption and mineral ingestion is protective against MS, we aimed to characterize the effects of 8weeks of natural mineral-rich water consumption on the structural organization and expression of vascular growth factors and receptors on the corpus cavernosum （CC） in 10% fructose-fed Sprague-Dawley rats （FRUCT）. Differences were not observed in the organization of the CC either on the expression of vascular endothelial growth factor （VEGF） or the components of the angiopoietins/Tie2 system. However, opposing expression patterns were observed for VEGF receptors （an increase and a decrease for VEGFR1 and VEGFR2, respectively） in FRUCT animals, with these patterns being strengthened by mineral-rich water ingestion. Mineral-rich water ingestion （FRUCTMIN） increased the proportion of smooth muscle cells compared with FRUCT rats and induced an upregulatory tendency of sirtuin I expression compared with the control and FRUCT groups. Western blot results were consistent with the dual immunofluorescence evaluation. Plasma oxidized low-density lipoprotein and plasma testosterone levels were similar among the experimental groups, although a tendency for an increase in the former was observed in the FRUCTMIN group. The mineral-rich water-treated rats presented changes similar to those observed in rats treated with MS-protective polyphenol-rich beverages or subjected to energy restriction, which led us to hypothesize that the effects of mineral-rich water consumption may be more vast than those directly observed in this study.

EGCG恢复Sirt-1拮抗高糖诱导的PC12细胞凋亡

目的:探讨表没食子儿茶素没食子酸酯(EGCG)对高糖诱导的PC12细胞损伤的保护作用及Sirt-1的介导机制。方法:CCK-8法检测PC12细胞活力; ELISA法检测Bcl-2的活性;免疫荧光法检测Caspase-3在胞质的活性及胞核内DAPI的表达; WB检测Sirt-1的表达。结果:高浓度的葡萄糖(15、30、45 mmol/L)诱导了PC12细胞的损伤,细胞活性较对照组分别下降了14%、32%及57%,凋亡保护蛋白Bcl-2的表达较对照组下降了8%、30%及35%; EGCG(10、20、40μmol/L)对高糖诱导的PC12细胞凋亡提供了保护作用,细胞活性较高糖损伤组分别提升了2%、20%及24%,Bcl-2的表达提升了10%、22%和25%;阻断Sirt-1通路逆转了EGCG提供的保护作用,同时加入阻断剂组的细胞活性较EGCG保护组下降了8%,Bcl-2的表达下降了16%。结论:EGCG通过恢复Sirt-1活性拮抗高糖诱导的PC12细胞的凋亡。

LIN28A attenuates high glucose-induced retinal pigmented epithelium injury through activating SIRT1-dependent autophagy

AIM:To evaluate the effects of LIN28A(human)on high glucose-induced retinal pigmented epithelium(RPE)cell injury and its possible mechanism.METHODS:Diabetic retinopathy model was generated following 48h of exposure to 30 mmol/L high glucose(HG)in ARPE-19 cells.Quantitative real-time polymerase chain reaction(qRT-PCR)and Western blot tested the expression of the corresponding genes and proteins.Cell viability as well as apoptosis was determined through cell counting kit-8(CCK-8)and flow cytometry assays.Immunofluorescence assay was adopted to evaluate autophagy activity.Caspase 3 activity,oxidative stress markers,and cytokines were appraised adopting their commercial kits,respectively.Finally,ARPE-19 cells were preincubated with EX527,a Sirtuin 1(SIRT1)inhibitor,prior to HG stimulation to validate the regulatory mechanism.RESULTS:LIN28A was downregulated in HG-challenged ARPE-19 cells.LIN28A overexpression greatly inhibited HGinduced ARPE-19 cell viability loss,apoptosis,oxidative damage as well as inflammatory response.Meanwhile,the repressed autophagy and SIRT1 in ARPE-19 cells challenged with HG were elevated after LIN28A overexpression.In addition,treatment of EX527 greatly inhibited the activated autophagy following LIN28A overexpression and partly abolished the protective role of LIN28A against HG-elicited apoptosis,oxidative damage as well as inflammation in ARPE-19 cells.CONCLUSION:LIN28A exerts a protective role against HG-elicited RPE oxidative damage,inflammation,as well as apoptosis via regulating SIRT1/autophagy.

SIRT1 facilitates amyloid beta peptide degradation by upregulating lysosome number in primary astrocytes

Previous studies have shown that sirtuin 1（SIRT1） reduces the production of neuronal amyloid beta（Aβ） and inhibits the inflammatory response of glial cells, thereby generating a neuroprotective effect against Aβ neurotoxicity in animal models of Alzheimer＇s disease. However, the protective effect of SIRT1 on astrocytes is still under investigation. This study established a time point model for the clearance of Aβ in primary astrocytes. Results showed that 12 hours of culture was sufficient for endocytosis of oligomeric Aβ, and 36 hours sufficient for effective degradation. Immunofluorescence demonstrated that Aβ degradation in primary astrocytes relies on lysosome function. Enzymatic agonists or SIRT1 inhibitors were used to stimulate cells over a concentration gradient. Aβ was co-cultured for 36 hours in medium. Western blot assay results under different conditions revealed that SIRT1 relies on its deacetylase activity to promote intracellular Aβ degradation. The experiment further screened SIRT1 using quantitative proteomics to investigate downstream, differentially expressed proteins in the Aβ degradation pathway and selected the ones related to enzyme activity of SIRT1. Most of the differentially expressed proteins detected are close to the primary astrocyte lysosomal pathway. Immunofluorescence staining demonstrated that SIRT1 relies on its deacetylase activity to upregulate lysosome number in primary astrocytes. Taken together, these findings confirm that SIRT1 relies on its deacetylase activity to upregulate lysosome number, thereby facilitating oligomeric Aβ degradation in primary astrocytes.

野黄芩苷通过刺激Sirtuin1/Nrf2/HO-1信号通路改善阿尔茨海默症大鼠学习记忆能力

目的验证野黄芩苷通过刺激去乙酰化酶1(sirtuin 1)/核因子E-2相关因子(nuclear factor E2 related factor 2,Nrf2)/血红素加氧酶1(heme oxygenase 1,HO-1)信号通路改善阿尔茨海默病(Alzheimer′s disease,AD)大鼠学习记忆能力。方法60只健康成年雄性SD大鼠按随机数字表法分入6组(每组10只)。除阴性对照组外其他各组大鼠采用海马内注射人β-淀粉样蛋白1-42(amyloidβ1-42,Aβ1-42)制备AD模型;阴性对照组和模型组灌胃给予生理盐水(1 ml·kg^(-1)),野黄芩苷低剂量组、中剂量组和高剂量组分别灌胃给予野黄芩苷(10、20、40 mg·kg^(-1)),阳性对照组灌胃给予加兰他敏(3 mg·kg^(-1)),均1次·d-1,持续给予21 d。大鼠进行Morris水迷宫实验,取海马组织进行H-E染色和TUNEL染色,同时采用酶联免疫吸附(enzyme-linked immunosorbent,ELISA)法检测海马组织中超氧化物歧化酶(superoxide dismutase,SOD)、谷胱甘肽(glutathione,GSH)和丙二醛(malondialdehyde,MDA)水平,蛋白质印迹法检测海马组织中Sirtuin 1、Nrf2和HO-1蛋白水平。结果阴性对照组大鼠海马组织结构正常,染色质分布均匀,未见神经元坏死;模型组大鼠海马区神经元细胞排列紊乱,细胞核和细胞质分界不清,且存在大量神经元变性坏死;与模型组相比,各野黄芩苷剂量组和阳性对照组大鼠海马区细胞结构得以修复,神经元变性坏死减少。与阴性对照组比,其余各组大鼠目标象限游泳时间、平均游泳速度、SOD、GSH、Sirtuin 1、Nrf2和HO-1水平降低,细胞凋亡和MDA水平增加(P<0.05);与模型组比,各野黄芩苷剂量组和阳性对照组大鼠目标象限游泳时间、平均游泳速度、SOD、GSH、Sirtuin 1、Nrf2和HO-1水平增加,细胞凋亡和MDA水平降低,且各野黄芩苷剂量组之间呈剂量反应关系(P<0.05)。阳性对照组和野黄芩苷高剂量组各指标差异无统计学意义(P>0.05)。结论野黄芩苷可以改善AD大鼠学习记忆能力,其作用可能与Sirtuin1/Nrf2/HO-1信号通路激活有关。

Sirtuin1 attenuates acute liver failure by reducing reactive oxygen species via hypoxia inducible factor 1α

BACKGROUND The occurrence and development of acute liver failure(ALF)is closely related to a series of inflammatory reactions,such as the production of reactive oxygen species(ROS).Hypoxia inducible factor 1α(HIF-1α)is a key factor that regulates oxygen homeostasis and redox,and the stability of HIF-1αis related to the ROS level regulated by Sirtuin(Sirt)family.The activation of Sirt1 will lead to a powerful antioxidant defense system and therapeutic effects in liver disease.However,little is known about the relationship between HIF-1αand Sirt1 in the process of ALF and the molecular mechanism.AIM To investigate whether HIF-1αmay be a target of Sirt1 deacetylation and what the effects on ALF are.METHODS Mice were administrated lipopolysaccharide(LPS)/D-gal and exposed to hypoxic conditions as animal model,and resveratrol was used as an activator of Sirt1.The cellular model was established with L02 cells stimulated by LPS.N-acetyl-Lcysteine was used to remove ROS,and the expression of Sirt1 was inhibited by nicotinamide.Western blotting was used to detect Sirt1 and HIF-1αactivity and related protein expression.The possible signaling pathways involved were analyzed by immunofluorescent staining,co-immunoprecipitation,dihydroethidium staining,and Western blotting.RESULTS Compared with mice stimulated with LPS alone,the expression of Sirt1 decreased,the level of HIF-1αacetylation increased in hypoxic mice,and the levels of carbonic anhydrase 9 and Bcl-2-adenovirus E1B interacting protein 3 increased significantly,which was regulated by HIF-1α,indicating an increase of HIF-1αactivity.Under hypoxia,the down-regulation of Sirt1 activated and acetylated HIF-1αin L02 cells.The inhibition of Sirt1 significantly aggravated this effect and the massive production of ROS.The regulation of ROS was partly through peroxisome proliferatoractivated receptor alpha or AMP-activated protein kinase.Resveratrol,a Sirt1 activator,effectively relieved ALF aggravated by hypoxia,the production of ROS,and cell apoptosis.It also induced the deacetylation of HIF-1αand inhibited the activity of HIF-1α.CONCLUSION Sirt1 may have a protective effect on ALF by inducing HIF-1α deacetylation to reduce ROS.

High mobility group box-1 release from H2O2-injured hepatocytes due to sirt1 functional inhibition

BACKGROUND High mobility group box-1 (HMGB1), recognized as a representative of damageassociated molecular patterns, is released during cell injury/death, triggering the inflammatory response and ultimately resulting in tissue damage. Dozens of studies have shown that HMGB1 is involved in certain diseases, but the details on how injured hepatocytes release HMGB1 need to be elicited. AIM To reveal HMGB1 release mechanism in hepatocytes undergoing oxidative stress. METHODS C57BL6/J male mice were fed a high-fat diet for 12 wk plus a single binge of ethanol to induce severe steatohepatitis. Hepatocytes treated with H2O2 were used to establish an in vitro model. Serum alanine aminotransferase, liver H2O2 content and catalase activity, lactate dehydrogenase and 8-hydroxy-2- deoxyguanosine content, nicotinamide adenine dinucleotide (NAD+) levels, and Sirtuin 1 (Sirt1) activity were detected by spectrophotometry. HMGB1 release was measured by enzyme linked immunosorbent assay. HMGB1 translocation was observed by immunohistochemistry/immunofluorescence or Western blot. Relative mRNA levels were assayed by qPCR and protein expression was detected by Western blot. Acetylated HMGB1 and poly(ADP-ribose)polymerase 1 (Parp1) were analyzed by Immunoprecipitation. RESULTS When hepatocytes were damaged, HMGB1 translocated from the nucleus to the cytoplasm because of its hyperacetylation and was passively released outside both in vivo and in vitro. After treatment with Sirt1-siRNA or Sirt1 inhibitor (EX527), the hyperacetylated HMGB1 in hepatocytes increased, and Sirt1 activity inhibited by H2O2 could be reversed by Parp1 inhibitor (DIQ). Parp1 and Sirt1 are two NAD+-dependent enzymes which play major roles in the decision of a cell to live or die in the context of stress . We showed that NAD+ depletion attributed to Parp1 activation after DNA damage was caused by oxidative stress in hepatocytes and resulted in Sirt1 activity inhibition. On the contrary, Sirt1 suppressed Parp1 by negatively regulating its gene expression and deacetylation. CONCLUSION The functional inhibition between Parp1 and Sirt1 leads to HMGB1 hyperacetylation, which leads to its translocation from the nucleus to the cytoplasm and finally outside the cell.

Duodenal-jejunal bypass increases intraduodenal bile acids and upregulates duodenal SIRT1 expression in high-fat diet and streptozotocin-induced diabetic rats

BACKGROUND The mechanisms underlying diabetes remission after duodenal-jejunal bypass(DJB) remain elusive. In DJB surgery, the duodenum is excluded. However, the duodenum has emerged as an important regulator of glucose homeostasis, and elevated duodenal SIRT1 leads to improved hepatic insulin sensitivity. After DJB, bile acids(BAs) in the duodenum are not mixed and diluted by the ingested food. And activation of BA receptors promotes SIRT1 expression in many tissues. We hypothesized that BA-mediated upregulation of SIRT1 may contribute to diabetic control after DJB.AIM To investigate the surgical effects of DJB on duodenal SIRT1 expression and uncover the potential crosslinks between BAs and SIRT1.METHODS Twenty diabetic rats were randomly allocated to the sham(n = 10) and DJB(n = 10) groups. Body weight, food intake, fasting blood glucose(FBG), serum and intraduodenal total BA(TBA) levels were measured accordingly. Oral glucose tolerance test(OGTT) and intraperitoneal pyruvate tolerance test(ip PTT) were performed to evaluate the effects of surgeries on systemic glucose disposal and hepatic gluconeogenesis. The key genes of BA signaling pathway in the duodenal mucosa, including farnesoid X receptor(FXR), small heterodimer partner(SHP), and Takeda G-protein-coupled receptor 5(TGR5) were evaluated by real-time quantitative polymerase chain reaction 8 wk postoperatively. The duodenal SIRT1, AMPK, and phosphorylated AMPK(p-AMPK) levels were evaluated by western blotting. Rat small intestine epithelial IEC-6 cells were treated with GW4064 and INT-777 to verify the effects of BAs on SIRT1 expression in enterocytes.RESULTS The DJB group exhibited body weight and food intake comparable to those of the sham group at all postoperative time points. The FBG level and area under the curve for the OGTT and ip PTT were significantly lower in the DJB group. The DJB group exhibited higher fasting and postprandial serum TBA levels than the sham group at both 2 and 8 wk postoperatively. At 8 wk after surgery, the DJB group showed higher intraluminal TBA concentration, upregulated m RNA expression of FXR and SHP, and elevated protein expression of SIRT1 and p-AMPK in the descending and horizontal segments of the duodenum. Activation of FXR and TGR5 receptors by GW4064 and INT-777 increased the m RNA and protein expression of SIRT1 and promoted the phosphorylation of AMPK in IEC-6 cells.CONCLUSION DJB elevates intraduodenal BA levels and activates the duodenal BA signaling pathway, which may upregulate duodenal SIRT1 and further contribute to improved glucose homeostasis after DJB.

Molecular modeling of alkaloids bouchardatine and orirenierine binding to sirtuin-1(SIRT1)

Objective Bouchardatine(1)is a β-indoloquinazoline alkaloid isolated from the plant Bouchardatia neurococca,acting as a modulator of adipogenesis and lipogenesis,and as an anticancer agent.The natural product functions as an activator of proteins adenosine 5’-monophosphate(AMP)-activated protein kinase(AMPK)and sirtuin 1(SIRT1).We used molecular modeling to investigate the SIRT1-binding capacity of compound 1 and various structural analogues,such as orirenierine A(2)and orirenierine B(3)isolated from the medicinal plant Oricia renieri.Methods We investigated the binding to human SIRT1(hSIRT1)of 25 natural products including theβ-indoloquinazoline alkaloids 1−3 and analogues,in comparison with the reference product sirtinol(R and S isomers).A sirtinol binding model was elaborated starting from the closed and open state conformations of the catalytic domain of hSIRT1(PDB structures 4KXQ and 4IG9).For each compound bound to SIRT1,the empirical energy of interaction(ΔE)was calculated and compared to that of sirtinol.Results In our model,compound 1 was found to bind modestly to the sirtinol site of SIRT1.In contrast,the presence of a phenolic OH group at position 7 on the quinazolinone moiety conferred a much higher binding capacity.Compound 2 provided SIRT1 protein complexes as stable as those observed with sirtinol.The replacement of the hydroxy substituent(2)with a methoxy group(3)reduced the SIRT1 binding capacity.Other SIRT1-binding natural products were identified,such as the alkaloids orisuaveolines A and B.Structure-binding relationships were discussed.Conclusion The study underlines the capacity of β-indoloquinazoline alkaloids to interact with SIRT1.This deacetylase enzyme could represent a molecular target for the alkaloid 2.This compound merits further attention for the design of drugs active against SIRT1-dependent pathologies.

Induction of Sirtuin1 Activity in SH-SY5Y Cells by Cyanidin-3-O-Glucocide Induced

An increase in oxidative stress plays a key role in neurotoxicity induction and cell death, which leads to neurodegenerative diseases such as Parkinson’s disease and Alzheimer’s disease. Cyanidin-3-glucoside (C3G) is a common anthocyanin and shows antioxidant activity in neuronal cells. Silent information regulator 2-related protein 1 (Sirt1) regulates antioxidant and anti-inflammatory effects. However, the effects of C3G on Sirt1 in neuronal cells remain unclear. This study evaluated the effect of C3G on Sirt1 expression and activity in human neuroblastoma (SH-SY5Y) cells. In the study, C3G increased the expression of Sirt1 and Sirt1 activity in SH-SY5Y cells. Additionally, C3G increased the expression of nuclear factor erythroid 2-related factor 2, a vital transcription factor for regulating the expression of antioxidant genes, as well as antioxidant enzymes such as superoxide dismutase and catalase. Moreover, C3G protected SH-SY5Y cells from oxidative stress. These results suggest that C3G decreased oxidative stress-induced cell injury by increasing the expression of Sirt1 and other antioxidant factors. Therefore, C3G might merit further investigation for use in attenuating the progress of neurodegenerative diseases.