Silent Information Regulator 1 Expression Research Articles

Myostatin Knockout Affects Mitochondrial Function by Inhibiting the AMPK/SIRT1/PGC1α Pathway in Skeletal Muscle.

Myostatin (Mstn) is a major negative regulator of skeletal muscle mass and initiates multiple metabolic changes. The deletion of the Mstn gene in mice leads to reduced mitochondrial functions. However, the underlying regulatory mechanisms remain unclear. In this study, we used CRISPR/Cas9 to generate myostatin-knockout (Mstn-KO) mice via pronuclear microinjection. Mstn-KO mice exhibited significantly larger skeletal muscles. Meanwhile, Mstn knockout regulated the organ weights of mice. Moreover, we found that Mstn knockout reduced the basal metabolic rate, muscle adenosine triphosphate (ATP) synthesis, activities of mitochondrial respiration chain complexes, tricarboxylic acid cycle (TCA) cycle, and thermogenesis. Mechanistically, expressions of silent information regulator 1 (SIRT1) and phosphorylated adenosine monophosphate-activated protein kinase (pAMPK) were down-regulated, while peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) acetylation modification increased in the Mstn-KO mice. Skeletal muscle cells from Mstn-KO and WT were treated with AMPK activator 5-aminoimidazole-4-carboxamide riboside (AICAR), and the AMPK inhibitor Compound C, respectively. Compared with the wild-type (WT) group, Compound C treatment further down-regulated the expression or activity of pAMPK, SIRT1, citrate synthase (CS), isocitrate dehydrogenase (ICDHm), and α-ketoglutarate acid dehydrogenase (α-KGDH) in Mstn-KO mice, while Mstn knockout inhibited the AICAR activation effect. Therefore, Mstn knockout affects mitochondrial function by inhibiting the AMPK/SIRT1/PGC1α signaling pathway. The present study reveals a new mechanism for Mstn knockout in regulating energy homeostasis.

The effect of natural polyphenols Resveratrol, Gallic acid, and Kuromanin chloride on human telomerase reverse transcriptase (hTERT) expression in HepG2 hepatocellular carcinoma: role of SIRT1/Nrf2 signaling pathway and oxidative stress.

There is evidence that low doses or physiological concentrations of certain natural polyphenols enhance the activity of telomerase. However, the precise mechanism by which natural polyphenols regulate telomerase activity remains unclear. Recent research indicates that NF-E2 related factor 2 (Nrf2) and silent information regulator 1 (SIRT1) are involved in human telomerase reverse transcriptase (hTERT) regulation. Thus, in order to better comprehend the mechanism by which polyphenols regulate hTERT, the present study investigated the effects of the natural polyphenols Resveratrol, Gallic acid, and Kuromanin chloride on hTERT, Nrf2, and SIRT1 expression as well as oxidative stress in HepG2 hepatocellular carcinoma. The trypan blue dye exclusion assay was used to assess cell viability. The level of mRNA for hTERT, Nrf2, and SIRT1 was then determined using real-time PCR. A spectrophotometric analysis was conducted to quantify oxidative stress markers. The results demonstrated that Resveratrol induces the expression of hTERT and the SIRT1/Nrf2 pathway in a dose-dependent manner. Gallic acid at concentrations of 10 and 20μM also increased the expression of the hTERT and SIRT1/Nrf2 pathway. Furthermore, dose-dependent overexpression of hTERT and Nrf2 was induced by Kuromanin chloride at 10 and 20µM. Moreover, we found that Resveratrol and Kuromanin chloride ameliorated oxidative stress, whereas Gallic acid exacerbated it. This study demonstrates that low doses of polyphenols (Resveratrol, Gallic acid, and Kuromanin chloride) upregulate the expression of the hTERT gene in the HepG2 hepatocellular carcinoma cell line, possibly via induction of the SIRT1/Nrf2 signaling pathway. Therefore, by targeting this pathway or hTERT, the anti-cancer effect of polyphenols can be enhanced.

Regulation of radiation-induced liver damage by modulation of SIRT-1 activity: In vivo rat model.

Silent information regulator 1 (SIRT-1), a nicotinamide adenine dinucleotide-dependent deacetylase, was found to regulate cell apoptosis, inflammation, and oxidative stress response in living organisms. Therefore, the role of SIRT-1 in regulating forkhead box O/poly ADP-ribose polymerase-1 (FOXO-1/PARP-1) signaling could provide the necessary validation for developing new pharmacological targets for the promotion or inhibition of SIRT-1 activity toward radiation sensitivity. In the present study, the SIRT-1 signaling pathway is being investigated to study the possible modulatory effect of resveratrol (RSV, SIRT-1 activator) versus nicotinamide (NAM, SIRT-1 inhibitor) in case of liver damage induced by whole-body gamma irradiation. Rats were exposed to 6 Gy gamma radiation after being pretreated with either RSV (10 mg/kg/day) or NAM (100 mg/kg/day) for 5 days, and subsequent examining hepatic morphological changes and apoptotic markers were assessed. The expression of SIRT-1, FOXO-1, and cleaved PARP-1 in the liver was analyzed. RSV improved radiation-induced apoptosis, mitochondrial dysfunction, and inflammation signified by low expression of caspase-3, lactate dehydrogenase, complex-I activity, myeloperoxidase, and total nitric oxide content. RSV increased the expression of SIRT-1, whereas cleaved PARP-1 and FOXO-1 were suppressed. These protective effects were suppressed by inhibition of SIRT-1 activity using NAM. These findings suggest that RSV can attenuate radiation-induced hepatic injury by reducing apoptosis and inflammation via SIRT-1 activity modulation.

Dapagliflozin Protection against Myocardial Ischemia by Modulating Sodium-glucose Transporter 2 Inhibitor, Silent Information Regulator 1, and Fatty Acid Synthase Expressions

BACKGROUND: The emerging role of sodium-glucose transporter 2 (SGLT2) inhibitors drugs as potential therapeutic agents in myocardial ischemic (MI) injury treatment has raised the concern for possible mechanisms of action. AIM: The current experimental study aimed to investigate the possible protective effects of dapagliflozin (DAPA) a SGLT2i, on isoproterenol (ISO)-induced MI in rats. MATERIALS AND METHODS: Thirty Wistar rats were divided randomly and equally into three groups. Group 1 (control group): Received 1.0 mL of normal saline through an orogastric tube for 14 days. Group 2 (ISO group): Received 1.0 mL of normal saline orally through an orogastric tube for 14 days. In the last 2 days (days 13 and 14), ISO (100 mg/kg) was freshly dissolved in normal saline and injected subcutaneously once daily. Group 3 (ISO + DAPA-treated group): Received DAPA 1.0 mg/kg/day orally for 14 days. In the last 2 days (days 13 and 14), ISO (100 mg/kg) was introduced like that described in Group 2. RESULTS: DAPA protects MI development by reversal of blood pressure changes, electrocardiographic alterations, stabilization of cardiac enzymes, inflammation restoration, oxidative stress, and lipid profile. SGLT2 was overexpressed in the ISO-induced MI, which declined in the ISO + DAPA group. Moreover, DAPA induced silent information regulator 1 (SIRT1)/fatty acid synthase (FASN) overexpression in ISO-induced MI. DAPA could have a potential protective role against acute MI. CONCLUSION: DAPA protects against acute MI by modulating SIRT1 and FASN expression in cardiac muscles, suppressing oxidative stress, and downregulating inflammatory mediators.

Mesenchymal Stem Cell-Derived Exosomes Ameliorate Delayed Neurocognitive Recovery in Aged Mice by Inhibiting Hippocampus Ferroptosis via Activating SIRT1/Nrf2/HO-1 Signaling Pathway.

Delayed neurocognitive recovery (dNCR) is a prevalent perioperative neurological complication in older patients and has common characteristics such as acute cognitive dysfunction, impaired memory, and inattention. Mesenchymal stem cell-derived exosomes (MSCs-Exo) are enclosed by a lipid bilayer contain proteins, DNA, miRNA, and other components, which are important mediators of intercellular communication. It has been reported that exosomes could play an important role in the treatment of neurodegenerative diseases, nerve injury, and other neurological diseases. In this study, we examined the effects of MSCs-Exo on dNCR aged mice after exploratory laparotomy and evaluated their potential regulatory mechanisms. We found that MSCs-Exo treatment ameliorated cognitive impairment in dNCR aged mice. MSCs-Exo inhibit hippocampus ferroptosis and increase the expression of silent information regulator 1 (SIRT1), factor nuclear factor-erythroid 2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) in dNCR aged mice. Interestingly, the above effects of MSCs-Exo on dNCR aged mice were abolished by SIRT1 selective inhibitor EX-527. In conclusion, these findings indicated that MSCs-Exo can ameliorate cognitive impairment by inhibiting hippocampus ferroptosis in dNCR aged mice via activating SIRT1/Nrf2/HO-1 signaling pathway, providing a potential avenue for the treatment of dNCR.

Metformin mitigates cholesterol accumulation via the AMPK/SIRT1 pathway to protect osteoarthritis chondrocytes

In this study, we aim to investigate the effect of metformin on cholesterol synthesis and efflux-related genes in chondrocytes during osteoarthritis (OA) and explore the underlying mechanisms. Primary chondrocytes were harvested from Wistar rat cartilage and divided into control and treatment groups. Chondrocytes in the treatment group were treated with interleukin-1β (IL-1β) mimicking the inflammatory environment of osteoarthritis. Subsequently, RT-qPCR, Western blotting, immunofluorescence staining, and Cell Counting Kit-8 (CCK-8) were conducted. Significant reductions in phosphorylated AMP-activated protein kinase (p-AMPK) and silent information regulator 1 (SIRT1) protein expression were observed in both human OA chondrocytes and cultured primary murine chondrocytes treated with IL-1β, while AMP-activated protein kinase (AMPK) was not inhibited. Moreover, in the presence of IL-1β, metformin significantly increased the expression of p-AMPK and SIRT1 at the protein and mRNA level. Meanwhile, metformin could reverse IL-1β-induced cartilage extracellular matrix degradation in chondrocytes from the rat model of OA (treated by IL-β) by activating the AMPK/SIRT1 pathway. Moreover, metformin activated AMPK and SIRT1, mediated by the activation of SREBP-2 and HMGCR in OA chondrocytes. Inhibiting AMPK/SIRT1 activity by its specific inhibitor could suppress IL-1β-induced expression of LXRα, ABCA1 and ApoA1 and cholesterol efflux. Thus, metformin inhibits cholesterol synthesis and promotes cholesterol efflux by activating the AMPK/SIRT1 pathway in OA chondrocytes. This study improves our understanding of the effect of metformin on cholesterol accumulation in OA chondrocytes.

Correlation between serum SIRT1 and EZH2 expressions and peritoneal function in patients with diabetic nephropathy undergoing peritoneal dialysis.

To determine the correlation between the expression of silent information regulator 1 (SIRT1) and enhancer of zeste two polycomb repressive complex two subunit (EZH2) and peritoneal function in patients with diabetic nephropathy (DN) and peritoneal dialysis. One hundred forty patients with DN underwent peritoneal dialysis in Hanchuan People's Hospital from April 2016 to January 2019 were divided into four groups according to the duration of peritoneal dialysis. The levels of SIRT1 and EZH2 in serum were measured. The ratio of dialysate to plasma creatinine (D/Pcr) and the concentration of cancer antigen 125 (CA125) in peritoneal dialysate were determined. The ratio of urea clearance to urea distribution volume (Kt/V) of dialyzer was calculated. The correlations between SIRT1 and EZH2 expressions and peritoneal function were analyzed. With the prolongation of peritoneal dialysis, serum SIRT1 expression, Kt/V, Ccr and CA125 decreased, while EZH2 expression and D/Pcr increased in patients with DN undergoing peritoneal dialysis. Pearson's correlation analysis showed that SIRT1 expression was negatively correlated with D/Pcr while positively correlated with Kt/V and CA125, and serum EZH2 expression was negatively correlated with Kt/V and CA125 while positively correlated with D/Pcr. ROC analysis demonstrated that SIRT1 and EZH2 expressions had certain diagnostic value for the poor prognosis of patients with DN undergoing peritoneal dialysis. Serum SIRT1 and EZH2 expressions in patients with DN undergoing peritoneal dialysis are closely related to their peritoneal function. They have certain diagnostic value for the poor prognosis of patients with DN undergoing peritoneal dialysis.

Patchouli alcohol ameliorates the learning and memory impairments in an animal model of Alzheimer's disease via modulating SIRT1

BackgroundAlzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases. Patchouli alcohol (PA), a major active ingredient isolated from Pogostemonis Herba, exhibits extensive bioactivity in the central nervous system (CNS) and exerts neuroprotective effects. PurposeThis study aimed to investigate the anti-AD effects of PA in an animal model of AD and to elucidate the underlying molecular mechanisms. MethodsThe gas chromatography (GC) was used to determine the ability of PA to pass the blood-brain barrier (BBB) in rats after oral administration. The sporadic AD rat model was established by intracerebroventricularly (ICV) injection with streptozotocin (STZ). PA (25 and 50 mg/kg) was given to rat orally once daily for 42 consecutive days. Morris water maze (MWM) test was performed to determine the learning and memory functions of the STZ-induced AD rats. EX527, a silent information regulator 1 (SIRT1) selective inhibitor, was used to investigate the involvement of SIRT1 in the anti-AD effects of PA in rats. ResultsPA could penetrate the BBB. MWM test results showed that PA could significantly ameliorate the learning and memory deficits induced by STZ in rats. Meanwhile, PA enhanced the expression of SIRT1, and markedly alleviated the tau pathology by inhibiting the hyperacetylation (at the site of Lys174) and hyperphosphorylation (at the sites of Thr181, Thr205, Ser396 and Ser404) of tau protein. PA also efficiently suppressed the activation of microglia and astrocytes, and the beta-amyloid (Aβ) expression and the deacetylation of nuclear factor-kappa B (NF-κB) at Lys 310 (K310) in the STZ-treated AD rats. EX527, a SIRT1 selective inhibitor, could partially abolish the cognitive deficits improving effect of PA and inhibit the down-regulation of acetylated tau and acetylated NF-κB p65, suggesting that PA exhibited neuroprotective effects against AD via upregulating SIRT1. ConclusionThis study reported for the first time that PA could penetrate the BBB to exert its protective effects on the brain after a single-dose oral administration. The current experimental findings also amply demonstrated that PA could improve the cognitive and memory impairments in the STZ-induced AD rat model. The underlying mechanisms involve the alleviations of neuroinflammation, tau pathology and Aβ deposition via modulating of SIRT1 and NF-κB pathways. All these findings strongly suggest that PA is a promising naturally occurring compound worthy of further development into an anti-AD pharmaceutical.

Resveratrol protection against IL-1β-induced chondrocyte damage via the SIRT1/FOXO1 signaling pathway

PurposeOsteoarthritis (OA) is a common joint disease characterized by cartilage degeneration, synovial inflammation, osteophytes, and subchondral osteosclerosis. This study investigated the effects of resveratrol (RES) on extracellular matrix (ECM), autophagy, and apoptosis in OA pathogenesis via the SIRT1/FOXO1 pathway.MethodsThe microenvironment of OA chondrocytes was stimulated in vitro by adding 10 ng/mL of IL-1β to primary Wistar rat chondrocyte. Western blotting, immunofluorescence, quantitative real-time PCR, and transmission electron microscopy (TEM) were used for analysis.ResultsIn the presence of IL-1β, RES increased the expression of silent information regulator (SIR) 1 protein and the phosphorylation level of forkhead transcription factor (FOXO) 1. It also promoted chondrocyte autophagy, increased the expression of SOX9 and aggrecan, inhibited chondrocyte apoptosis and matrix breakdown, and protected chondrocytes from IL-1β damage. After a SIRT1 inhibitor or FOXO1 inhibitor was added, the protective effect of RES on chondrocytes was significantly weakened. Our results suggest that RES regulates the ECM metabolism, autophagy, and apoptosis of OA chondrocytes through the SIRT1/FOXO1 pathway to ameliorate IL-1β-induced chondrocyte injury.ConclusionRES protects chondrocytes from IL-1β-induced damage by activating SIRT1/FOXO1 signaling and holds potential in OA treatment.

Effects of SIRT1 in amygdala on chronic restraint stress-induced depression-like behaviors in rats

To investigate the effects of silent information regulator 1 (SIRT1) in amygdala on depression-like behaviors in rats using chronic restraint stress (CRS) as a model of depression. Sixty male SD rats were randomly divided into six groups (n=10 per group): control group (Control), chronic restraint stress group (CRS), CRS + fluoxetine-treated group (CRS + FLU), CRS + saline-treated group (CRS + NaCl), CRS + SIRT1-overexpression group (CRS + AAV-SIRT1), and CRS + empty vector group (CRS + AAV-EGFP). Except for the control group, rats from the other groups were exposed to chronic restraint stress for 21 days. After the modeling, rats in fluoxetine-treated group and saline-treated group were, respectively, treated with fluoxetine (10 mg/kg) or saline (10 mg/kg) by gavage every day for 3 weeks; AAV-SIRT1 or AAV-EGFP was, respectively, stereotaxically injected into the amygdala of rats in SIRT1-overexpression group and empty vector group, and the virus was expressed for 3 weeks. Rats in normal control group and CRS model group were not given any drug treatment. The depression-like behaviors of rats in each group were evaluated by sugar preference test (SPT), open field test (OFT) and forced swimming test (FST). SIRT1 expression in amygdala of rats was assessed by using immunoblot blotting. The number of SIRT1-positive cells in amygdala of rats was detected by immunofluorescence technique. Compared with the normal control group, the level of SIRT1 protein and the number of SIRT1+ cells in amygdala of the CRS-exposed rats were decreased significantly (P＜0.01), and CRS-exposed rats showed a significant decrease in sucrose preference (P＜0.01), less total horizontal distance (P＜0.01) and less time entered the center field (P＜0.01) in the OFT, a significant increase in the immobility time of the FST (P＜0.01). Fluoxetine treatment (P＜0.05, P＜0.01) or SIRT1 overexpression (P＜0.01) partially reversed the down-regulation of SIRT1 protein and SIRT1+ cells in amygdala of CRS-exposed rats and significantly improved the depression-like behaviors of CRS rats. Fluoxetine treatment partially reversed the down-regulation of SIRT1 level and the number of SIRT1+ in CRS rats, and significantly improved the depression-like behaviors. The antidepressant effect of fluoxetine treatment may be related to the up-regulation of SIRT1 in the amygdala of CRS-exposed rats.

Exosome Derived from Mesenchymal Stem Cells Alleviates Pathological Scars by Inhibiting the Proliferation, Migration and Protein Expression of Fibroblasts via Delivering miR-138-5p to Target SIRT1.

IntroductionThe therapies of using exosomes derived from mesenchymal stem cells (MSC-Exo) for wound healing and scar attenuation and micro RNAs (miRNAs) for regulation of genes by translational inhibition and mRNA destabilization obtained great achievements. Silent information regulator 1 (SIRT1) is the silent information, which has an intricate role in many biological processes. However, the effects of SIRT1 and miR-138-5p loaded in MSC-Exo on pathological scars remain unclear.MethodsMSC-Exo was isolated and identified by ultracentrifugation, transmission electron microscopy, nanoparticle size measuring instrument and Western blot assays. The relationship between SIRT1 and miR-138-5p was verified by a double-luciferase reporter assay. Cell Counting Kit-8, Τranswell, scratch, and Western blot assays were used to evaluate the proliferation and migration of human skin fibroblasts (HSFs), and the protein expression of SIRT1, NF-κB, α-SMA and TGF-β1 in HSFs, respectively. Flow cytometry was used to assess the apoptosis and cell cycle of HSFs affected by SIRT1.ResultsOur study demonstrated that miR-138-5p loaded in MSC-Exo could attenuate proliferation, migration and protein expression of HSFs-derived NF-κB, α-SMA, and TGF-β1 by targeting to SIRT1 gene, which confirmed the potential effects of MSC-Exo in alleviating pathological scars by performing as a miRNA’s delivery vehicle.ConclusionExosomes derived from MSCs acting as a delivery vehicle to deliver miR-138-5p can downregulate SIRT1 to inhibit the growth and protein expression of HSFs and attenuate pathological scars.

Targeting SIRT1 Rescues Age- and Obesity-Induced Microvascular Dysfunction in Ex Vivo Human Vessels.

Background:Experimental evidence suggests a key role of SIRT1 (silent information regulator 1) in age- and metabolic-related vascular dysfunction. Whether these effects hold true in the human microvasculature is unknown. We aimed to investigate the SIRT1 role in very early stages of age- and obesity-related microvascular dysfunction in humans.Methods:Ninety-five subjects undergoing elective laparoscopic surgery were recruited and stratified based on their body mass index status (above or below 30 kg/m2) and age (above or below 40 years) in 4 groups: Young Nonobese, Young Obese, Old Nonobese, and Old Obese. We measured small resistance arteries’ endothelial function by pressurized micromyography before and after incubation with a SIRT1 agonist (SRT1720) and a mitochondria reactive oxygen species (mtROS) scavenger (MitoTEMPO). We assessed vascular levels of mtROS and nitric oxide availability by confocal microscopy and vascular gene expression of SIRT1 and mitochondrial proteins by qPCR. Chromatin immunoprecipitation assay was employed to investigate SIRT1-dependent epigenetic regulation of mitochondrial proteins.Results:Compared with Young Nonobese, obese and older patients showed lower vascular expression of SIRT1 and antioxidant proteins (FOXO3 [forkhead box protein O3] and SOD2) and higher expression of pro-oxidant and aging mitochondria proteins p66Shc and Arginase II. Old Obese, Young Obese and Old Nonobese groups endothelial dysfunction was rescued by SRT1720. The restoration was comparable to the one obtained with mitoTEMPO. These effects were explained by SIRT1-dependent chromatin changes leading to reduced p66Shc expression and upregulation of proteins involved in mitochondria respiratory chain.Conclusions:SIRT1 is a novel central modulator of the earliest microvascular damage induced by age and obesity. Through a complex epigenetic control mainly involving p66Shc and Arginase II, it influences mtROS levels, NO availability, and the expression of proteins of the mitochondria respiratory chain. Therapeutic modulation of SIRT1 restores obesity- and age-related endothelial dysfunction. Early targeting of SIRT1 might represent a crucial strategy to prevent age- and obesity-related microvascular dysfunction.

PBX1-SIRT1 Positive Feedback Loop Attenuates ROS-Mediated HF-MSC Senescence and Apoptosis

Stem cell senescence and depletion are major causes of aging and aging-related diseases. The NAD (Nicotinamide adenine dinucleotide) – SIRT1 (Silent Information Regulator 1) – PARP1 (Poly (ADP-ribose) polymerase-1) axis has gained interest owing to its significant role in regulating stem cell senescence and organismal aging. A recent study from our lab showed that pre-B-cell leukemia transcription factor1 (PBX1) overexpression attenuates hair follicle-derived mesenchymal stem cells (HF-MSCs) senescence and apoptosis by regulating ROS-mediated DNA damage via PARP1 downregulation; thus, suggesting that PARP1 downregulation is a common manifestation of the roles of both PBX1 and SIRT1 in HF-MSCs senescence attenuation, and implying a potential link between PBX1 and SIRT1. To this end, HF-MSCs overexpressing PBX1, overexpressing both PBX1 and PARP1, downregulating SIRT1, and overexpressing PBX1 as well as downregulating SIRT1 were generated, and senescence, apoptosis, DNA damage, and repair biomarkers were analyzed. Our results showed that (1) PBX1 overexpression alleviated HF-MSCs senescence and apoptosis accompanied by SIRT1 upregulation, PARP1 downregulation, and increased intracellular NAD and ATP levels. (2) SIRT1 knockdown enhanced cellular senescence and apoptosis, accompanied by increased ROS accumulation, DNA damage aggravation, and decreased intracellular NAD and ATP levels. (3) PBX1 overexpression rescued HF-MSCs senescence and apoptosis induced by SIRT1 knockdown. (4) PBX1 rescued PARP1 overexpression-mediated ATP and NAD depletion, accompanied by increased SIRT1 expression. Collectively, our results revealed that a positive interaction feedback loop exists between PBX1 and SIRT1. To the best of our knowledge we are the first to report that there is a PBX1-SIRT1-PARP1 axis that plays a critical role in alleviating HF-MSCs senescence and apoptosis. We provide a new perspective on the mechanisms underlying stem cell senescence as well as age-related disease prevention and treatment.Graphical

AMPK/SIRT1 Deficiency Drives Adjuvant-Induced Arthritis in Rats by Promoting Glycolysis-Mediated Monocytes Inflammatory Polarization.

BackgroundExact roles of many metabolic regulators in rheumatoid arthritis (RA) are to be clarified. This study aimed to further characterize the impacts of silent information regulator 1 (SIRT1) status changes on this disease.MethodsFluctuation pattern of SIRT1 expression in adjuvant-induced arthritis (AIA) rats was monitored using periodically collected white blood cells. Another bath of AIA rats were treated by SIRT1 agonist resveratrol. Blood from these rats was used to separate monocytes and plasma, which were subjected to polymerase chain reaction (PCR), enzyme linked immunosorbent assay (ELISA), and biochemical analyses. Clinical implication of SIRT1 activation was verified by treating AIA rat monocytes with SIRT1 agonist and overexpression vector in vitro.ResultsSIRT1 deficiency occurred in AIA rats, which was accompanied with down-regulation of interleukin 10 (IL-10) and arginase-1 (ARG-1). Resveratrol eased oxidative stress and increased IL-10 production in vivo. Results of ELISA analysis demonstrated that resveratrol attenuated AIA severity in rats. Furthermore, it restored the altered levels of triglyceride, lactate and pyruvate in blood. Resveratrol promoted IL-10 production, and suppressed glycolysis of AIA monocytes cultured in vitro. SIRT1 overexpression similarly reshaped differentiation profile of AIA monocytes, evidenced by changes in metabolism indicators, IL-10 production and AMP-activated protein kinase (AMPK) pathway status. Although overexpressing SIRT1 in normal cells did not affect glycolysis significantly, it attenuated AMPK antagonist-caused abnormality.ConclusionSIRT1 deficiency is implicated in AIA-related immune abnormality and metabolism alteration. Activating this signaling with resveratrol would impair the inflammatory polarization of monocytes, and consequently ease the severity of RA.

Tamoxifen induced hepatic steatosis in high-fat feeding rats through SIRT1-Foxo1 suppression and LXR-SREBP1c activation.

Clinically, long-term use of tamoxifen (TAM) would lead to fatty liver disease in breast cancer patients, especially obese women. However, the exact mechanism of TAM-induced hepatic steatosis is still unclear. Meanwhile, there is no drug to prevent and treat it. In view of silent information regulator 1 (SIRT1) playing a key role in hepatic lipid metabolism regulation, this study was conducted to investigate whether SIRT1 is a potential therapeutic target for TAM-induced hepatic steatosis. In this study, obese female Wistar rats fed with high-fat diet (HFD) for 15weeks were given TAM (4, 8mg/kg, intragastric) for 14days. In vitro, human hepatocarcinoma cell line HepG2 was used to establish a high-fat model with 50μM oleic acid and TAM (10μM) was treated simultaneously for 72h. The results showed that TAM was more likely to upregulate the expression of lipid synthetase that caused the increase of lipid content in HepG2 cells and rat liver. The expression of SIRT1 was downregulated both in vitro and in vivo. SIRT1 agonist SRT1720 (15mg/kg, 30mg/kg, i.p.) could resist TAM-induced hepatic lipid synthetase overexpression to relieve TAM-induced hepatic steatosis. Meanwhile, the upregulation of p-forkhead box O1 and LXRα induced by TAM was reversed by SRT1720. These results indicated that TAM-induced hepatic steatosis was based on SIRT1-p-FoxO/LXRα-sterol regulatory element binding protein 1c pathway under HFD condition. SIRT1 agonist might be a potential therapeutic drug to relieve this side effect. Tamoxifen increased lipid synthesis and regulated lipid transport in HFD rat liver.p-FoxO1/LXRα-SREBP1c signaling was upregulated through the inhibition of SIRT1 in tamoxifen-induced hepatic steatosis under HFD condition.SIRT1 agonist SRT1720 could relieve tamoxifen-induced hepatic steatosis.

SIRT1 modifies DNA methylation linked to synaptic deficits induced by Pb in vitro and in vivo

To investigate the mechanism of Silent information regulator 1 (SIRT1) regulation of DNA methylation and thus the expression of synaptic plasticity-related genes induced by lead (Pb) exposure, the early-life Sprague-Dawley rats and PC12 cells were used to establish Pb exposure models and treated with SIRT1 agonists (resveratrol and SRT1720). In vivo results demonstrated that Pb exposure increased the expression of DNMTs, MeCP2, PP1 and cleaved caspase3, decreased the expression of SIRT1, BDNF and RELIN and altered DNA methylation levels of synaptic plasticity genes. Moreover, we observed marked pathological damage in the hippocampal CA1 region of the 0.2 % Pb-exposure group. After treatment with resveratrol, the effects of Pb exposure on the expression of the above molecules and pathological features were significantly ameliorated in the hippocampus of rats. In vitro results showed that after the treatment with SRT1720, the expression of SIRT1 was activated and thus reversed the effect on DNMTs, MeCP2, apoptosis and synaptic plasticity-related genes and their DNA methylation levels induced by Pb exposure. In conclusion, we validated the important protective role of SIRT1 in neurotoxicity induced by Pb exposure through in vivo and in vitro experiments, providing potential therapeutic targets for the treatment and prevention of brain damage.

Tianma Gouteng Decoction regulates MFN2 expression to delay vascular aging in spontaneously hypertensive rats

We studied the effect of Tianma Gouteng Decoction on vascular aging in spontaneously hypertensive rats(SHRs) to explore the molecular mechanism of the decoction in improving arterial vascular aging by regulating the expression of mitofusin 2(MFN2).Twenty 64-weeks-old SHRs were randomly assigned into the aging group and the treatment group(Tianma Gouteng Decoction 5.48 mg·kg~(-1)).Wistar-Kyoto(WKY) rats of 64 weeks old were taken as the normal group and SHR rats of 14 weeks old as the young group.The intervention with Tianma Gouteng Decoction lasted for 12 weeks.We then employed HE staining and Masson staining to observe the morphology of thoracic aorta under an electron microscope and measured the malondialdehyde(MDA) content, superoxide dismutase(SOD) activity, respiratory chain complex Ⅲ level, and thioredoxin peroxidase(TPX) activity.The vascular aging was detected via the biomarker senescence-associated beta-galactosidase(SA-β-Gal).The expression levels of MFN2 and aging marker proteins silent information regulator 1(SIRT1), Klotho, p21, and p53 in thoracic aorta were detected by immunohistochemistry/fluorescence, qRT-PCR, and Western blot.Compared with the young group and the normal group, the aging group had risen blood pressure, lumen stenosis caused by thickened intima of blood vessels, decreased SOD and TPX activities, increased MDA and mitochondrial respiratory chain complex Ⅲ levels, down-regulated expression of MFN2, SIRT1, and Klotho, and up-regulated expression of p21 and p53(P<0.01 or P<0.05).The treatment with Tianma Gouteng Decoction significantly lowered blood pressure, mitigated vascular intimal thickening, increased SOD and TPX activities, and decreased MDA and mitochondrial respiratory chain complex Ⅲ levels, thus alleviating vascular aging.At the same time, the decoction up-regulated the expression of MFN2, SIRT1, and Klotho, while down-regulated that of p21 and p53(P<0.01 or P<0.05).In summary, Tianma Gouteng Decoction can significantly delay the vascular aging in hypertension.Specifically, it may up-regulate the expression of MFN2 and regulate the expression of aging-related proteins to alleviate oxidative stress.

P-714 Visfatin and Silent Information Regulator 1 (SIRT1) in Pakistani infertile females

Abstract Study question What is the relationship of SIRT1 and oxidative stress markers with obesity among infertile Pakistani females? Summary answer Progressive decline in antioxidants with the increase in BMI suggests that obesity causes oxidative stress that consequently leads to infertility in females. What is known already Deficiency of Silent Information Regulator 1 (SIRT1) can trigger inflammation, mitochondrial malfunctioning and apoptosis through the hypothalamic-pituitary-ovarian axis, producing poor quality oocytes, triggering obesity and associated metabolic disorders. SIRT1 expression levels are higher in endocrine system dysfunctions. Obesity has a potential risk for subfertility, infertility, deteriorated embryo quality, decreased endometrial receptivity, implantation failure and increased miscarriage rates. Visfatin increases in response to low levels antioxidants in obese, and its expression is negatively associated with the antioxidants produced. It disturbs glucose metabolism and promotes obesity, rendering it a powerful candidate as an OS marker. Study design, size, duration This cross-sectional study was conducted from August 2017 – July 2019, at Aga Khan Hospital in collaboration with Australian Concept Infertility Medical Centre (ACIMC) on 207 fertile and 135 infertile female subjects were recruited after ethical approval from of Aga Khan Hospital (AKU-ERC-2018-0557-601). Participants/materials, setting, methods kg)/height in meters (m2). Females were categorized by South-Asian criteria of BMI (normal-weight=18.0-22.9; overweight = 23-24.9; obese >25.0 kg/m2). Commercially available ELISA kits were used for estimation of serum Manganese Superoxide Dismutase (MnSOD), Glutathione Reductase (GR), visfatin and SIRT1. Pearson Chi-Square test and ANOVA were applied to compare the means within BMI groups. Association of variables was observed by Spearman correlation with significance at p < 0.05. Main results and the role of chance The mean BMI was 25.94 ± 5.1 kg/m2; 27.5% of females were normal-weight, 22.8% overweight, while 40.9% were obese. BMI was significantly high in infertile subjects (p < 0.001). MnSOD, visfatin and GR were lower in infertile females, decreasing from normal-weight to obese (p < 0.001). Increase in BMI was associated with a decrease in SIRT1 and antioxidants levels in both fertile and infertile females. Limitations, reasons for caution The small sample size was a limitation of the current study due to financial constraints, on the basis of which measurement of other non-enzymatic antioxidants such as malondialdehyde (MDA), glutathione, total antioxidant capacity (TAC), nitric oxide (NO) and reactive oxygen species could not be made possible. Wider implications of the findings SIRT1 is a fascinating target in various disease situations due to the promise of pharmacological and/or natural modulators of SIRT1 activity within the framework of endocrine and immune-related disease models. Trial registration number non applicable

Role of MST1 in the regulation of autophagy and mitophagy: implications for aging-related diseases.

As a key mechanism to maintain cellular homeostasis under stress conditions, autophagy/mitophagy is related to the occurrence of metabolic disorders, neurodegenerative diseases, cancer, and other aging-related diseases, but the relevant signal pathways regulating autophagy have not been clarified. Mammalian sterile 20-like kinase 1 (MST1) is a central regulatory protein of many metabolic pathways involved in the pathophysiological processes of aging and aging-related diseases and has become a critical integrator affecting autophagic signaling. Recent studies show that MST1 not only suppresses autophagy through directly phosphorylating Beclin-1 and/or inhibiting the protein expression of silent information regulator 1 (SIRT1) in the cytoplasm, but also inhibits BCL2/adenovirus E1B protein-interacting protein 3 (BNIP3)-, FUN14 domain containing 1 (FUNDC1)-, and Parkin (Parkinson protein 2)-mediated mitophagy by interacting with factors such as Ras association domain family 1A (RASSF1A). Indeed, a common pharmacological strategy for anti-aging is to induce autophagy/mitophagy through MST1 inhibition. This article reviews the role and mechanism of MST1 in regulating autophagy during aging, to provide evidence for the development of drugs targeting MST1.

Danshensu prevents thrombosis by inhibiting platelet activation via SIRT1/ROS/mtDNA pathways without increasing bleeding risk

BackgroundCoronary thrombosis and its correlated disorders are main healthcare problems globally. The therapeutic effects of current treatments involving antiplatelet drugs are not fully satisfactory. Danshensu (DSS) is an important monomer obtained from Salvia miltiorrhiza roots that have been widely employed for vascular diseases in medicinal practices. Nonetheless, the underlying mechanisms of DSS are not fully unraveled. PurposeThe objective of this study was to penetrate the antithrombotic and antiplatelet mechanisms of DSS. MethodsNetwork pharmacology assay was used to forecast the cellular mechanisms of DSS for treating thrombosis. The work focused the impacts of DSS on platelet activation by analyzing aggregation and adhesion in vitro. Flow cytometry, western blotting, CM-H2DCFDA staining and mitochondrial function assays were performed to reveal the molecular mechanisms. The model of common carotid artery thrombus induced by ferric chloride was established. The wet weight of thrombus was measured, and the thrombosis was observed by hematoxylin and eosin (H&E) staining, in order to support the inhibitory effect of DSS on thrombosis. ResultsData mining found the antithrombotic effect of DSS is related to platelet activation and the core target is silent information regulator 1 (SIRT1). We confirmed that DSS dose-dependently inhibited platelet activation in vitro. DSS was further demonstrated to induce the expression of SIRT1 and decreased reactive oxygen species (ROS) burden and thereby prevented mitochondrial dysfunction. Mitochondrial function tests further indicated that DSS prevented mitochondrial DNA (mtDNA) release, which induced activation of platelet in a dendritic cell specific intercellular-adhesion-molecule-3 grabbing non-integrin (DC-SIGN)-dependent manner. In carotid artery injury model induced by ferric chloride, DSS inhibited the development of carotid arterial thrombosis. More encouragingly, in tail bleeding time assay, DSS did not augment bleeding risk. ConclusionThese findings indicated that DSS effectively inhibited platelet activation by depressing the collection of ROS and the release of platelet mtDNA without arousing hemorrhage risk. DSS might represent a promising candidate drug for thrombosis and cardiovascular disease therapeutics.